Roger Federer began the defence of his Dubai Open title with a 7-6, 6-3 win over Swiss compatriot Stanislas Wawrinka on Tuesday in his first match since winning the Australian Open.
He was joined in the second round by number two seed Rafael Nadal, who was stretched by Frenchman Paul-Henri Mathieu before winning 6-7, 6-1, 6-2.
The Spanish teenager received a walkover into the quarter-finals after his next opponent, Younes El Aynaoui of Morocco, withdrew from the tournament for personal reasons.
Federer had to work hard for his victory against an opponent who rallied well, made few unforced errors, and changed the pace to good effect.
Both players needed to resist a pair of break points in the middle of the first set, before Federer took the tiebreak 7-3.
In the second set, seven of the nine games went against serve, with Federer holding for 3-2 and 6-3. Despite being put under pressure the world number one said he was not surprised.
"I thought my game was coming and going," Federer told reporters. "My serve wasn't that great in the beginning and then I really got a high percentage going and then it left me again.
Nadal proved his fitness after a recent lengthy period of injury when he resisted a strong challenge from Mathieu.
HIGH QUALITY
In a match of the highest quality, the players tested each other in some furiously-contested rallies which thrilled the late-evening crowd.
Mathieu fought off two break points at 3-3 with some powerful serves, held a set point at 6-5 which he lost with a poor return, but then forced a backhand error to claim the tiebreak.
He failed to maintain the rallies as well in the second set, though, as Nadal raised his game to another level and the Spanish left-hander broke for 2-0 and 5-1 when Mathieu netted two forehands.
Nadal continued his momentum into the final set, breaking for 2-1, and when he virtually tied up the match with a further break for 4-1 a frustrated Mathieu smashed his racquet.
"In the first set I had a lot of chances," said Nadal. "I had two 0-30s, one 15-40 and I played defensively and for that I lost the set. After, in the second and third set, I changed my approach. I played more aggressively, a more intense match.
"It was an important match for me because I lost the first set and came back with a very good physical performance," he added. "I ran very well to difficult balls and that's important because the foot is very good now."
Russia's Marat Safin made an impressive return from a six-month injury layoff to beat compatriot and world number five Nikolay Davydenko 4-6, 6-2, 6-2.
Safin had not played since August after a knee ligament tear suffered at Wimbledon became too painful for him to continue.
"I didn't expect to win. It was a big surprise," Safin said.
"Especially with the draw, I couldn't really think I would make even a set. I was coming out to play a few games and make sure I was moving okay and get back the rhythm.
"I still have a little bit of pain, but it's not the same pain as it used to be and I can move without any problems."
