Elise Mertens had lost in the first round of the Qatar Open in 2018
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.
