WTA Fourth Round tips: Gauff's five-win streak meets Mertens challenge

Coco Gauff's unbeaten surge through the draw meets Elise Mertens' gritty campaign in Wednesday's Fourth Round, with the world No. 4 American carrying a five-match winning streak into the 2:00 pm AEDT start. Gauff hasn't dropped a set since August and swept aside her most recent opponent in straight sets on Tuesday, while Mertens — ranked 19th — enters off back-to-back straight-set victories of her own. The gulf in rankings tells part of the yarn, but Mertens' 331-win career and ten titles suggest a player who won't fold under pressure.

Form collides with firepower in a contest that shapes the top half of the bracket. Gauff's consistency has been the story of her campaign; Mertens' resilience and court craft could pose the first genuine test. Our tennis predictions and best bets unpack the matchup, dissect the set handicap, and weigh whether the scoreboard pushes past 19.5 games.

Who will win?

Gauff's form line reads like a tour highlight reel: five wins on the trot, all in straight sets bar none. Coming off a 7–6(5), 6–1 demolition on Tuesday, she's carried that momentum through home conditions in her last two starts — the most recent a clinical display, the one before a three-set grind against Camila Osorio where she closed 7–6, 6–2 after dropping the second. Before that, three away victories in August, each wrapped up in two. The American hasn't tasted defeat since early August, and her ranking — fourth in the world with 7,244 points — reflects a player in career-best touch.

Mertens arrives with her own narrative: a two-match winning burst that includes Monday's 6–3, 6–2 dismantling of Jelena Ostapenko and Saturday's 6–4, 7(0)–6, 6–5 escape against Katie Volynets. Her last four starts show three wins and one loss — the setback a straight-sets defeat to Naomi Osaka at home in early August. The Belgian's 331-213 career record (61 per cent) and ten titles speak to a player who's navigated big stages before, but her recent home form — one win, one loss in her last two — lacks the consistency Gauff's been stacking up.

The head-to-head ledger is silent, which adds intrigue but shifts the weight onto current form. Gauff's five-win run, her ranking advantage, and her ability to close out tight matches give her the edge. The market agrees: she's priced as the strong favourite, and punters have backed that assessment. Mertens will need to produce the best tennis of her campaign to upset the rhythm Gauff's built, but her experience and title pedigree mean she'll at least make it interesting.

Sets handicap: can Mertens stay within range?

The set handicap sits at 1.5, asking whether Mertens can pinch at least one set to stay within the line. Gauff's last five starts have been ruthless — five straight-set victories, with only one opponent (Osorio) extending her to a third. That's as clean a recent record as you'll find, and it's built on a blend of power and poise that's dismantled ranked opposition without fuss.

Mertens' recent form offers mixed signals. Her last two wins were straight-set affairs, but the Volynets match went the distance and the Osaka loss in August was a swift two-setter where she managed just one game in the decider. Her ability to grind — evidenced by that three-set win over Volynets — gives her a path to nicking a set if Gauff's level dips, but the American's consistency suggests that dip might not arrive. The Belgian's career numbers (62 per cent win rate this year) hint at a player who can hang around, but Gauff's current run feels like a different gear entirely.

For Mertens to cover the 1.5-set line, she'll need to conjure the sort of performance that's eluded her against top-ten opposition lately. Gauff's form says she'll take this in straights more often than not, leaving the set handicap a question of whether the underdog can manufacture one competitive frame. The evidence leans toward Gauff sweeping through, but Mertens' experience keeps the door slightly ajar.

Total games: will it run long?

The total games line is pegged at 19.5, which splits the difference between a brisk straight-setter and a match that extends into a third set. Gauff's recent wins have been efficient — her Tuesday victory wrapped up in 13 games (7–6, 6–1), and her Osorio clash totalled 22 games across three sets. The American's ability to close out tight first sets (7–6 twice in her last five) keeps scorelines from blowing out, but her dominance in second and third frames (6–1, 6–2 finishes) can compress the total when she gets rolling.

Mertens' last two matches totalled 15 games (Ostapenko) and 19 games (Volynets), the latter pushed to three sets. Her Osaka loss was a quick 13-game affair, while her earlier home win went 19 games across three. The Belgian's recent form suggests she's capable of stealing a set and nudging the scoreboard higher, but she's also been swept aside when outclassed. The absence of any previous meetings leaves us guessing at the dynamic, but the quality gap tilts toward efficiency.

If Gauff finds her range early, this could settle comfortably under 19.5 games — a straight-set finish in the 12-to-16-game range feels plausible given her recent ruthlessness. Mertens' best chance of pushing the total over involves dragging Gauff into a tiebreak or nicking the first set, but the American's form suggests she'll dictate tempo and close the door before the scoreboard climbs. The under carries the weight of Gauff's momentum, but one tight set could flip the script.