DOHA: Elise Mertens has claimed the biggest title of her career by beating top seed Simona Halep to win the Qatar Open. Mertens, 23, recovered from a set and a break down - losing 18 points in a row at one stage in the second set - to beat the world number three 3-6 6-4 6-3. World number 21 Mertens also overcame a lengthy medical time-out for a back issue in the first set. "Simona is a great player and it's nice to get the trophy," the Belgian said. Halep, 27, who last won the Qatar title in 2014, said: "Honestly, I wanted to lift this beautiful trophy but Elise deserved it very much." Mertens' triumph over the Romanian was her third win over a top 10 player in Doha. She had already beaten Angelique Kerber and Kiki Bertens, a year after she was knocked out of the tournament in the first round. Halep outclassed her opponent in the opening set, but Mertens powered back into the match to force a decider. The players traded breaks in the third set, but Mertens broke in the fifth game of the final set to make it 3-2 - the 12th break of serve in 24 games in the match. Halep tried to rally, but at at 5-3 and appearing to be hampered by an injury, she lost her serve, handing Mertens a famous victory.