Heather Watson has withdrawn from the TEB BNP Paribas Tennis Championship after feeling unwell during her first round clash with Sara Sorribes Tormo.
The fifth seed called for assistance at 2-3 in the first set in Istanbul and took a three-minute medical time-out after an initial assessment, during which her blood pressure and temperature were taken.
She was treated as she lay on a towel at the side of the court, but was eventually forced to retire.
Watson had got off to a poor start when she was broken in the opening game, and then had to survive two break points in the third before ending consecutive rallies with delicate drop shots to fight back and open her account.
The 28-year-old levelled at 2-2 after setting up break point with an angled backhand volley, but surrendered parity immediately after netting another attempted drop shot having looked uncomfortable as the game approached its conclusion.
In other news, Kei Nishikori was beaten in his return to professional tennis after a one-year break, losing to Miomir Kecmanovic 4-6 6-4 6-2 in the first round of the Generali Open.
Fabio Fognini is the top-seeded player at the clay-court event, which was rescheduled from July and is the first European tournament on the ATP Tour since Marseille in February.
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