Roger Federer began the defence of his Dubai Open title with a 7-6 6-3 win over Swiss compatriot Stanislas Wawrinka 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.
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.
