DOHA, Qatar (AP) — Defending champion Roger Federer was tested for the first time Thursday at the Qatar Open before defeating Andreas Seppi of Italy 6-3, 5-7, 6-4 to reach the semifinals.

The third-ranked Federer set up a rematch of last year’s semifinal against Jo-Wilfried Tsonga, after the Frenchman cruised past unseeded Albert Ramos of Spain 6-2, 6-1.

The 30-year-old Federer is aiming for his fourth Doha title.

Federer, who had never dropped a set against Seppi in seven wins, took a 3-0 lead in just six minutes and appeared en route to an easy victory. But he unraveled in the second set, going down 5-1 after a string of unforced errors coupled with improved returns from the 38th-ranked Italian.

Federer came back to tie the set at 5-all but Seppi took the last two games, evening the match when the 16-time Grand Slam champion hit his return long.

Federer recovered in the third, breaking Seppi to go up 2-1. He saved two break points to take control at 5-3 and closed out the match with a blistering forehand winner into the corner which Seppi couldn’t reach.

The sixth-ranked Tsonga struggled to three-set wins in his first two matches.

However, he broke Ramos in the first game and was never seriously challenged. He broke again to go up 5-2, and took a 4-1 lead in the second set, repeatedly pumping his fists when he hit winners and dancing as he closed out the match in just over an hour.

“I was very aggressive at the very beginning with my play, so I did well today,” said Tsonga, who joked this week that he was normally a “diesel engine” who starts slowly.

Tsonga said he was pleased with his serving, winning 83 percent of the first-serve points.

“It was good, because I had a good percentage. With the wind, I think it’s a good weapon,” he said. “When the wind is across the court, you know, I can slice the ball.

“This is my best serve. When I play a lefty guy, it’s easier for me to put him out of the court. Then the court is open for me and it’s easy.”

In other quarterfinals, Rafael Nadal plays Mikhail Youzhny, while Gael Monfils meets Viktor Troicki of Serbia.