Australian Open champion Novak Djokovic and top seed Roger Federer survived early onslaughts to reach the semi-finals of the Dubai championships on Thursday.
Djokovic recovered to beat Germany's Florian Mayer 7-5 6-1 and Federer defeated Ukraines's Sergiy Stakhovsky 6-3 6-4.
The second-seeded Serbian will next play third seed Tomas Berdych after the Czech defeated another German, Philipp Petzschner 7-5 6-4, while Federer faces unseeded Richard Gasquet, who overcame Gilles Simon 5-7 6-2 6-4 in an all-French quarter-final.
Djokovic, bidding to win the title for the third successive year, was rocked by Mayer's early challenge, dropping his serve in the opening game and then fighting off two break points at 0-2 before holding on his fourth game point.
The Serb then settled down and won his next three service games without losing a point and, down 4-5, he broke Mayer to love, held off a break point in the next game with an ace and then broke Mayer to love again to take the set.
In the second set Mayer averted a break point in the second game but made a forehand error to fall behind 3-1 and Djokovic then dominated the rest of the match.
"It was a very slow start," Djokovic told reporters. "Quite different conditions from last night's match. The ball was going faster today, and he took it to me from the start. Already first game he was on the net, twice, three times. You know, I was not moving my legs well.
"But when I needed to play well and needed to keep the ball in the court, I did."
Federer also conceded his serve in the first game, but levelled at 1-1 when he floated a backhand return and then held the next game with four consecutive aces after being down 0-40.
A forehand pass gave Federer a second break for 5-3, and he broke again to take a 2-1 lead in the second set when Stakhovsky netted a forehand.
Federer was then placed under pressure, needing to hold off a break point at 3-2 and two more at 4-3. He then held three match points on Stakhovsky's serve at 5-3 before closing out the match in the next game.
"I thought it was a tough match, tougher than the last couple, just because the start of the match, obviously that was tricky, the first sort of three, four games, where it could be 3-Love for him, could be 2-1 for me, could be 3-1, 2-All, or whatever," said Federer.
"So important to stay with him there, and then sort of finding the rhythm, how to play him, how is he playing, how is he serving, is he coming in, is he staying back, what's his strengths, what are his weaknesses?
"So it was just a matter of trying to figure him out, and I thought actually I played a really good match for the remainder of the game. You know, at the end, I'm obviously happy. It's been maybe a routine score, but, you know, I had to work for it tonight."