Aryna Sabalenka's march through 2026 hit a rare speed bump last Sunday when Ekaterina Alexandrova pulled off a three-set upset, snapping the Belarusian's winning run at two matches. Now the world No.1 faces Maria Camila Osorio Serrano in Tuesday's First Round clash at 4:30 am AEST, and the bookmaker has her at the very short end of the market to make amends.

Sabalenka has been a wrecking ball this season — 40 wins against eight losses, three titles already in the bag, and a career win rate sitting at 74 per cent. Osorio Serrano, ranked 58th and carrying a 15–16 year-to-date ledger, has never beaten the top seed in two previous meetings and arrives as a massive underdog. The yarn here is simple: can the Colombian spring a shock, or does Sabalenka roll through in straight sets?

Who will win?

Sabalenka's last outing was a grind she couldn't finish — up two sets before Alexandrova clawed back to take it 4–6, 4–6, 7–4, 6–4, 6–4 on hard court. Before that stumble, the world No.1 had pieced together two straight wins, both in straight sets, suggesting the engine was purring nicely until Sunday's wobble. Her 40–8 year-to-date record and 83 per cent win rate this season tell the broader story: she's been clinical more often than not.

Osorio Serrano's 15–16 record this year paints a different picture — she's hovered around the .500 mark and sits well outside the top 50. The head-to-head ledger offers no comfort either: Sabalenka prevailed in straight sets both times they've met, once on grass in 2021 (6–0, 6–3) and again on clay in April 2023 (6–4, 7–5). The Colombian has yet to pinch a set off the Belarusian, let alone a match.

The market reflects that gulf. Sabalenka is priced at the prohibitive end for the match winner, while Osorio Serrano sits out at double digits. For punters chasing tennis predictions this week, the value conversation moves quickly past the head-to-head and into the handicap and totals.

Head to HeadOdds correct as at 3:18 am AEST. Odds can change.
Our tipMarta Kostyuk1.11Sloane Stephens6.70
High confidenceOur tip: Aryna Sabalenka. The world No.1 has never lost to Osorio Serrano in two meetings and boasts a 40–8 year-to-date record. Coming off a rare loss, Sabalenka should be motivated to reset against a familiar opponent.

Tipped at $1.05 (12:12 pm AEST). Opinion, not a guarantee. Gamble responsibly — 18+.

Head-to-head context

1–0

Marta Kostyuk vs Sloane Stephens

Hard1-0
100%1st set → match win % (H2H)0%
0%Deciding set win % (H2H)0%
74%1st serve points won %54%
50%Return points won %39%

Sets Handicap

The Sets line has Sabalenka laying 1.5 sets, meaning she needs a straight-sets victory to cover. Given her 2–0 head-to-head record — both wins coming in two — and Osorio Serrano's struggles to keep pace with the top tier, the favourite covering the spread feels like the logical path.

Sabalenka's recent form shows she can put opponents away quickly when firing. Two of her last three starts ended in straight sets, and even the loss to Alexandrova saw her win the opening two frames before the wheels came off. Osorio Serrano, meanwhile, has shown little to suggest she can push a player of Sabalenka's calibre to a decider. The -1.5 sets line looks fair, and the favourite has the firepower to deliver.

SetsOdds correct as at 3:18 am AEST. Odds can change.
Our tipMarta Kostyuk -1.51.45Sloane Stephens +1.52.75
High confidenceOur tip: Aryna Sabalenka -1.5. Sabalenka has won both previous encounters in straight sets, and Osorio Serrano has yet to take a set off her. The favourite's ability to dominate makes covering the spread the likely outcome.

Tipped at $1.35 (12:12 pm AEST). Opinion, not a guarantee. Gamble responsibly — 18+.

Set handicap (±1.5) form

−1.5 cover = won by two or more sets. Charts use recent completed scorelines.

Marta Kostyuklast 5

−1.5 cover rate40%2/5
+1.5 cover rate80%4/5
Straight-sets wins40%2/5

Sloane Stephenslast 5

−1.5 cover rate60%3/5
+1.5 cover rate80%4/5
Straight-sets wins60%3/5
40%−1.5 cover % (form)60%
H2H −1.5 cover (Marta Kostyuk)100%1/1

Total Games

The Total Games line sits at 18.5, and the history between these two offers a tidy guide. Their April 2023 meeting on clay totalled 20 games (6–4, 7–5); the July 2021 grass-court encounter finished at 15 (6–0, 6–3). That's an average of 17.5 games across the two matches — just under the current line.

Sabalenka's ability to dominate service games and break at will against lower-ranked opponents suggests a brisk affair is on the cards. If the world No.1 clicks into gear early and Osorio Serrano can't find answers on serve, this one could wrap up in fewer than 19 games. The under looks the sharper play.

GamesOdds correct as at 3:18 am AEST. Odds can change.
Over 19.52.05Our tipUnder 19.51.75
Medium confidenceOur tip: Under 18.5. The two prior meetings averaged 17.5 total games, just below the current line. If Sabalenka clicks early, this match wraps up quickly.

Tipped at $1.90 (12:12 pm AEST). Opinion, not a guarantee. Gamble responsibly — 18+.

Match total games

Average games from recent scorelines · marker shows live line 19.5.

Marta Kostyuk matches (n=5)avg 22.4vs 19.5
1528
Sloane Stephens matches (n=5)avg 21.2vs 19.5
1528
H2H meetings (n=1)avg 24vs 19.5
1528

Hit rate vs 19.5

Marta Kostyukn=5
Over 60%Under 40%
Sloane Stephensn=5
Over 60%Under 40%
H2Hn=1
Over 100%Under 0%
12.6Avg games won (form)11.4

The verdict

Sabalenka needs to shake off the Alexandrova loss, and facing an opponent she's never dropped a set against is the ideal tonic. Osorio Serrano has fought gamely this season to stay competitive, but the gap in class and the head-to-head form point to a straightforward result. The favourite should win, and win quickly.

For punters weighing up the angles, the Sets Handicap and Total Games markets offer more appealing odds than the prohibitive match-winner line. Sabalenka's track record against Osorio Serrano and her ability to close out matches in two sets make the -1.5 spread and the under on total games the logical landing spots.