No.5 seed Jelena Ostapenko came out on top of a rollercoaster first round at the Mubadala Abu Dhabi Open, edging Danielle Collins 7-5, 1-6, 7-5 in 2 hours and 18 minutes.

Ostapenko, who collected her fifth and most recent title in Dubai last February, is now on a six-match winning streak on Emirati soil. It was her second win in as many meetings at pro level with Collins; the Latvian also triumphed 7-6(1), 6-3 in the 2018 Miami semifinals.

No.12-ranked Ostapenko is fresh off a run to the Australian Open quarterfinals last month, and will face either Zheng Qinwen or qualifier Rebecca Marino in the second round.

Meanwhile on Day 1, Marta Kostyuk pulled off a remarkable drop shot from the baseline en route to her 6-2, 1-6, 6-2 first-round win over Sorana Cirstea.

Turning points: The clash between two of the tour's foremost exponents of first-strike power was characterised by unpredictable momentum swings. In the first set, No.42-ranked Collins made the first move, breaking Ostapenko with a clean return winner for 4-3. But the American double faulted down break point when serving for the set, and it was Ostapenko who stole the opening act with a four-game run.

Former Australian Open finalist Collins responded superbly in the second set, with three consecutive return winners paving the way to a double-break lead and setting the tone for a one-sided passage of play. But Ostapenko wrested momentum back after capturing a titanic tussle at the start of the decider, converting her fifth break point to lead 2-1.

Three double faults in one game from the former Roland Garros champion allowed Collins to draw level at 4-4, but in the home stretch it was Ostapenko who was both more aggressive and more clutch. From 5-4 down, she powered through 12 of the last 15 points to seal victory.

By the numbers: The final stat sheet was in Collins' favour: 33 winners (including 11 aces) to Ostapenko's 30 (including six aces), an equal number of unforced errors (44 apiece) and fewer double faults (seven to nine).

But one meaningful disparity in the pairs' numbers was in the effectiveness of the second serve. Collins took just five of 19 points behind it in the first set, and seven of 17 in the third; overall, her second serve winning percentage was 37% compared to Ostapenko's 49%.

Indeed, Ostapenko's second serve winning percentages in the first and third sets were a decent 67% and 53% respectively. In the middle set, it was not so much her second serve as both deliveries that let her down, garnering her only five points on serve in total.

In Ostapenko's words: "Danielle is a great player, and it's always a tough match against her because she plays really well and she's such a fighter. The match is never over until we shake hands. I'm really glad that, even though in some games I didn't play my best, I was fighting and I managed to win the match. These kinds of matches give confidence.