Game plan

Serena Williams v Kimberly Birrell

Every number combines what Serena Williams does well with what Kimberly Birrell allows, each measured against the tour average and shrunk toward it when the sample is thin. Flip perspective

Forecast

Serena Williams wins, best of 3 100%90%: 98%–100% · best of 5: 100%

Serve points won 70.2% / 49.5% Serena / Kimberly · tour 56.4%

Strengths only, no similarity priors 100%serve 70.3% / 49.7%

Each player's serve and return strength is fitted against every opponent they were charted against, so a record built on weak opponents counts for less. At least one of them is no longer active or has too little charted in the last three seasons, so both are compared on their careers. The result is then nudged by Serena Williams's record against Kimberly Birrell's tactical lookalikes and in their charted head-to-heads (lookalikes: −2.0 on serve, +4.9 on return vs expectation (141 points)). A game-by-game Markov chain turns point odds into match odds; the 90% range covers the uncertainty in the two strengths, not the nudges. Charted matches lean toward big events, so treat this as a scouting estimate, not a betting line.

Head to head, per 100 shots

Career	Serena	Kimberly
Direction choice	+0.34 ±0.04 better than 97%	−0.11 ±0.18 better than 34%
Shot selection	+0.47 ±0.05 better than 93%	+0.29 ±0.15 better than 77%
Execution	−0.04 ±0.27 better than 59%	−1.63 ±0.97 better than 8%
Points left on the table	2.20 ±0.07 lower than 94%	2.49 ±0.27 lower than 67%

Each player's career against an average tour player in the same position, adjusted for opponent strength, with a 90% margin (shots clustered by match). Points left on the table is the gap to the best-value direction for the same stroke, so lower is better. Percentiles are within each player's own tour. A side is highlighted only when the gap is larger than the margin on the difference.

Serve plan

The share of points the server wins when a first serve lands in that direction (hover a rate for its 90% interval; ± is the 90% margin). "Matchup" combines the server's rate with how this returner handles that serve. "Optimal" is the mix that wins most against this returner once they start reading a habit, at the response measured across the tour, and only within the range servers' habits actually vary. The gain over the current mix is how exploitable that mix is.

Serena Williams serving

Deuce court

1st serve	Now	Serena wins	v Kimberly	Matchup	Optimal
Wide	50%	70%	74%	77.7%±5.9	43% ▼
Body	8%	62%	60%	64.8%±9.6	0% ▼
T	42%	79%	75%	84.6%±4.8	57% ▲

Optimal v Kimberly Birrell: +0.8±0.8 per 100 first serves (faults included) over the current mix. Serving T every time would read +5.0 per 100 first serves in before the returner adjusts.

Ad court

1st serve	Now	Serena wins	v Kimberly	Matchup	Optimal
Wide	45%	75%	78%	84.4%±4.8	36% ▼
Body	6%	60%	58%	62.1%±10.7	0% ▼
T	49%	70%	78%	81.5%±5.5	64% ▲

Optimal v Kimberly Birrell: +0.7±0.8 per 100 first serves (faults included) over the current mix, inside the 90% margin. Serving wide every time would read +2.8 per 100 first serves in before the returner adjusts.

Kimberly Birrell serving

Deuce court

1st serve	Now	Kimberly wins	v Serena	Matchup	Optimal
Wide	43%	55%	65%	54.1%±7.1	52% ▲
Body	30%	59%	53%	55.2%±8.2	15% ▼
T	27%	67%	66%	64.7%±8.4	33% ▲

Optimal v Serena Williams: +0.6±0.8 per 100 first serves (faults included) over the current mix, inside the 90% margin. Serving T every time would read +7.5 per 100 first serves in before the returner adjusts.

Ad court

1st serve	Now	Kimberly wins	v Serena	Matchup	Optimal
Wide	32%	62%	66%	62.4%±8.3	42% ▲
Body	25%	53%	57%	53.9%±8.8	30% ▲
T	43%	60%	61%	56.5%±7.5	28% ▼

Optimal v Serena Williams: +0.1±0.8 per 100 first serves (faults included) over the current mix, inside the 90% margin. Serving wide every time would read +4.6 per 100 first serves in before the returner adjusts.

Return plan

Value of each return, in points per 100 returns against an average return of the same serve (direction, court, surface): the tour's result with that return, the returner's own edge with it, and what this server gives up when it comes back to that side. Returns with no charted direction are left out, so values compare with each other rather than with zero. Depth isn't a choice here: missed returns have no depth. Serve quality isn't charted, so a block through the middle partly reflects the serve that forced it.

Serena Williams returning

1st serve to the forehand

Return	Now	Tour	Own	v Kimberly	Value
FH through the middle	49%	+4.2	−2.6	+1.9	+3.4±2.2
FH crosscourt	36%	+5.3	−1.6	−3.0	+0.7±3.4
FH down the line	11%	+1.5	−0.4	+3.2	+4.3±4.2
BH through the middle	1%	+5.2	−3.4	+3.1	+5.0±2.7
FH slice through the middle	1%	−6.7	−0.7	+0.5	−6.9±1.9

Lean BH through the middle: +2.5±3.2 per 100 returns v the current mix (2166 returns charted, inside the 90% margin)

1st serve to the backhand

Return	Now	Tour	Own	v Kimberly	Value
BH through the middle	48%	+6.0	+0.3	+3.1	+9.4±2.1
BH crosscourt	33%	+7.7	+1.3	−0.9	+8.1±2.9
BH down the line	12%	+2.2	+1.1	−2.3	+1.0±4.2
BH slice through the middle	3%	−6.2	−4.5	−0.1	−10.8±2.4
BH slice crosscourt	2%	−4.2	−2.8	−1.5	−8.4±2.5

Lean BH through the middle: +2.6±1.5 per 100 returns v the current mix (1939 returns charted)

2nd serve to the forehand

Return	Now	Tour	Own	v Kimberly	Value
FH crosscourt	43%	+0.5	−0.5	+2.5	+2.5±3.8
FH through the middle	37%	−3.2	−0.1	+1.7	−1.6±2.7
FH down the line	18%	−0.6	+5.3	+2.2	+7.0±4.8
BH inside-in	1%	+2.0	−1.4	+3.7	+4.2±3.5
BH through the middle	1%	−1.0	−0.2	+0.7	−0.5±2.2

Lean FH down the line: +5.2±4.4 per 100 returns v the current mix (750 returns charted)

2nd serve to the backhand

Return	Now	Tour	Own	v Kimberly	Value
BH crosscourt	51%	+1.5	+0.9	+3.7	+6.0±3.0
BH through the middle	30%	−2.6	−1.8	+0.7	−3.7±2.4
BH down the line	17%	−0.5	+3.4	−2.4	+0.4±4.6
FH inside-in	1%	+0.7	+0.7	+2.5	+3.9±4.0
FH inside-out	1%	+1.4	+0.2	+2.2	+3.7±3.5

Lean BH crosscourt: +4.0±1.8 per 100 returns v the current mix (954 returns charted)

Kimberly Birrell returning

1st serve to the forehand

Return	Now	Tour	Own	v Serena	Value
FH through the middle	48%	+4.2	−2.6	−1.3	+0.2±2.4
FH down the line	30%	+1.5	−4.7	−1.4	−4.6±3.9
FH crosscourt	22%	+5.3	+0.2	−4.0	+1.5±3.5

Lean FH crosscourt: +2.5±3.2 per 100 returns v the current mix (151 returns charted, inside the 90% margin)

1st serve to the backhand

Return	Now	Tour	Own	v Serena	Value
BH through the middle	48%	+6.0	−1.1	−1.0	+3.9±2.3
BH crosscourt	37%	+7.7	−3.1	−0.2	+4.3±3.1
BH down the line	12%	+2.2	−3.0	−4.1	−5.0±3.7
BH slice down the line	4%	−12.5	−0.7	−1.2	−14.3±2.9

Lean BH crosscourt: +2.0±2.3 per 100 returns v the current mix (128 returns charted, inside the 90% margin)

2nd serve to the forehand

Return	Now	Tour	Own	v Serena	Value
FH through the middle	43%	−3.2	−0.8	−0.9	−4.9±2.4
FH crosscourt	34%	+0.5	−0.6	−3.0	−3.0±3.6
FH down the line	23%	−0.6	+0.7	+0.6	+0.8±4.0

Lean FH crosscourt: −0.1±2.7 per 100 returns v the current mix (56 returns charted, inside the 90% margin)

2nd serve to the backhand

Return	Now	Tour	Own	v Serena	Value
BH through the middle	48%	−2.6	+0.7	−0.3	−2.1±2.2
BH crosscourt	40%	+1.5	−2.0	−0.2	−0.7±2.9
BH down the line	13%	−0.5	−0.4	−2.1	−3.0±3.8

Lean BH crosscourt: +1.0±2.1 per 100 returns v the current mix (86 returns charted, inside the 90% margin)

Rally plan

Edge, in points per 100 shots: the hitter's skill with the shot (own) plus how much the receiver usually gives up against it (theirs), both measured against the tour average on hard. Each player's hard record is shrunk toward their all-surface one, so a thin sample on it moves the numbers only a little.

Serena Williams

Favour

Shot	Edge	Own	Theirs
FH to their backhand · serve +1	+8.6±4.8	+3.4	+5.2
FH to their backhand · return	+7.8±5.0	+3.1	+4.6
FH to their backhand · rally	+4.3±3.6	+1.1	+3.2
BH to their backhand · return	+3.9±4.0	+0.4	+3.5
FH to their forehand · serve +1	+3.6±4.6	+1.9	+1.7
BH to their backhand · serve +1	+2.1±4.1	−1.7	+3.7

Avoid

Shot	Edge	Own	Theirs
FH to their backhand · return +1	−5.9±5.1	+1.7	−7.7
BH to their backhand · return +1	−2.4±3.9	−2.0	−0.4
FH to their forehand · return +1	−2.3±4.3	−3.0	+0.7
FH to their forehand · return	−2.3±4.8	−1.6	−0.7
BH to the middle · rally	−1.7±2.2	−1.2	−0.5

Kimberly Birrell

Favour

Shot	Edge	Own	Theirs
FH to the middle · serve +1	+3.8±3.0	+3.4	+0.4
BH to their backhand · return +1	+3.2±4.0	+0.9	+2.3
FH to their forehand · serve +1	+2.4±4.5	+2.3	+0.1
FH to their forehand · rally	+1.2±2.6	+0.5	+0.7
BH to their backhand · rally	+1.0±2.5	+0.6	+0.5
BH to the middle · return +1	−1.0±3.0	−0.1	−0.8

Avoid

Shot	Edge	Own	Theirs
BH to their forehand · return	−14.4±5.4	−10.1	−4.3
FH to their backhand · serve +1	−5.5±4.4	−3.1	−2.3
FH to their backhand · return	−5.4±5.2	−4.6	−0.8
FH to their forehand · return +1	−5.3±4.5	−6.2	+0.9
FH to their forehand · return	−4.8±5.0	−0.9	−3.9

Against Kimberly Birrell-like opponents

Serena Williams v	Matches	Serve pts won	Return pts won
All charted opponents	–	62.1%	45.1%
Players most similar to Kimberly Birrell	1	60.0%	50.0%

Similar by tactical fingerprint: Iva Jovic, Anastasia Potapova, Eva Lys, Anna Blinkova, Emma Navarro, Shuai Zhang, Emma Raducanu, Varvara Gracheva, Lin Zhu, R. When two players have rarely met, their records against these lookalikes fill the gap.