Fourth seed Nikolay Davydenko overcame an early fright to beat France's Florent Serra 6-7, 6-4, 6-1 on Tuesday in an error-strewn first-round battle at the Dubai Championships.
Sixth seed Marin Cilic had an easier time, thriving in the sweltering conditions to power past Frenchman Arnaud Clement 6-2, 6-4.
Fifth seed Jo-Wilfried Tsonga had just won the first set 7-6 when his opponent, fellow Frenchman and last week's Marseille Open winner Michael Llodra, pulled out with a hamstring injury.
Russian Mikhail Youzhny, the seventh seed, also defeated Slovak Lukas Lacko 6-7, 7-6, 6-1.
Davydenko, still struggling with a wrist injury suffered in Rotterdam this month, said he had been below par.
"Too many mistakes from me," the 28-year-old Russian told reporters.
"I had so many chances (to) make a break in the second set and win maybe more easily," he added.
Davydenko saved two set points to force a first-set tiebreak as both players made a succession of unforced errors.
Serra, 28, raced into a 6-2 tiebreak lead, hitting a brilliant forehand winner past Davydenko as the world number six approached the net. After saving another three set points, Davydenko finally succumbed, unable to return a blistering serve.
At 4-4 in the second set, Davydenko saved two break points. He made the first break of the match in the next game to clinch the second set.
The Russian then powered through the deciding set, losing only four points on his serve to set up a second-round clash with Germany's Michael Berrer, who defeated Ukrainian Sergiy Stakhovsky 6-4, 7-6.
Cilic, who has won two ATP events this year, will play qualifier Stefan Koubek in Wednesday's second round and the world number nine will not take his opponent lightly after the Austrian beat twice Dubai runner-up Feliciano Lopez on Monday.
"He won't be easy, he can be dangerous and I have to focus to serve good and try to play as aggressive as I can," said Cilic, who was unfazed by the heat.
"There were perfect conditions -- I like to play in the sun," said the 21-year-old Croatian, who dropped only five points on his serve in the first set.
The second set was tougher going and Clement, 32, saved two break points at 2-2 but then hit a double fault to gift the game to the 2010 Australian Open semi-finalist.
Cilic won the next game with a 201-kph ace to lead 4-2 and then put Clement's serve under pressure but the Frenchman saved another break point to pull back to 4-3.
Cilic eventually served out the match, saving five break points in the final game and clinching victory with an ace, his 13th of the contest.
Indian qualifier Somdev Devvarman beat Switzerland's Marco Chiudinelli 6-4, 7-5 to set up a meeting with Cypriot Marcos Baghdatis in the next round, while Spaniard Tommy Robredo defeated France's Julien Benneteau 6-2, 6-1.