EASTBOURNE, Great Britain -- Simona Halep began her 2019 grass-court season on the doubles court on Sunday, and the wait was worth it for her, as she and her fellow Romanian Raluca Olaru immediately busted open the Nature Valley International doubles draw with a first-round upset.

In the first doubles match of the tournament, Halep and Olaru knocked out No.1 seeds and defending champions Gabriela Dabrowski of Canada and Xu Yifan of China, 7-6(5), 7-5, to book their spot in the second round of the grass-court Premier event.

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Despite it being Halep's first grass-court match of the season in either singles or doubles, she and Olaru were able to maneuver their way back from deep deficits in each set to close out the clash in one hour and 34 minutes without the need of a decisive match-tiebreak.

The match was decided by very few points; the Romanian team had three more winners and one more unforced error than Dabrowski and Xu. Halep and Olaru converted five of ten break points, while the Canadian/Chinese pairing went 4-for-9 on break points.

In the opening set, Olaru dropped serve in her first two trips to the line, and the Romanians found themselves behind a double-break early as the defending champions moved to 5-2. Xu, however, was unable to serve out the set in that game, and Halep and Olaru pulled one break back.

Dabrowski then took a turn to try to close out the set at 5-4, but an excellent volley by Olaru erased a game point, and brought the game to deciding point. There, Xu missed a volley, and the Romanians had pulled all the way back level at 5-5.

The teams advanced to the first-set tiebreak, where a return winner by Olaru gave the Romanians an early 3-0 lead, but the top seeds regained parity at 3-3. The teams stayed on serve through 5-5, at which point Dabrowski missed a backhand just wide to queue up a first set point for Halep and Olaru. Olaru put away an overhead winner right away to close out the comeback opener for her team.

After an early exchange of breaks to open the second set, Xu slammed an overhead winner to break Olaru and put her tandem up 3-1. Dabrowski followed with a thunderous love service hold for 4-1, as the titleholders once again claimed a large early advantage.

However, on Xu's serve at 4-2, Dabrowski followed up a game-saving volley on break point with a long volley error on deciding point to allow the Romanians back on serve. Halep and Olaru did not look back from there, and they claimed a crucial lead as Olaru fired a down-the-line pass to break the No.1 seeds for 6-5.

With Olaru serving for the win, Halep knocked off an error-forcing backhand volley to bring her team to triple match point. Xu saved the first with a winning volley, and Olaru double faulted on the second, but on the third match point, Xu hit a return into the net, and Halep and Olaru attained their upset win.

Halep and Olaru will now await their second-round opponents, who will be either Alicja Rosolska of Poland and Yang Zhaoxuan of China, or Lucie Hradecka of the Czech Republic and Andreja Klepac of Slovenia.