By Matt Smith

DUBAI (Reuters) - Ana Ivanovic beat Anastasia Pavlyuchenkova 6-3 7-6 in the first round of the Dubai Tennis Championships on Monday, but Sloane Stephens was eliminated in three sets to cap a miserable debut trip to the Gulf for the U.S. teenager.

Ivanovic's career has dipped since she won the French Open in 2008, sinking from number one in the world rankings to 13, and she was far from flawless on the floodlit Dubai court.

The Serb slipped from 4-0 up in the second set to 6-6 before winning the subsequent tiebreak 7-5.

She was still too strong for 21-year-old Pavlyuchenkova, breaking in the first game and remaining largely in control thereafter, her Russian opponent's forehand too often found wanting to really put her higher-ranked adversary in trouble.

Ivanovic broke for a second time to go 4-1 up in the first set, a fierce cross-court return earning a break point she converted after Pavlyuchenkova thumped a forehand into the net.

Yet Ivanovic immediately lost her own serve to love as the world number 29 closed to 4-3 but the 25-year-old roused herself again, dropping only two points in the next two games as Pavlyuchenkova double-faulted to gift her the first set.

The Serb will now play Czech Petra Kvitova or Daniela Hantuchova in the second round.

Romania's Sorana Cirstea beat Stephens 5-7 6-3 6-2.

The American suffered a second-round exit in last week's Qatar Open and the world number 16 said she had found it tough going in her first trip to the Gulf.

"It's two tournaments to a place I have never been before, a very different situation for me," Stephens told reporters. "Some days you're going to be on court and it's not just going to turn out the way you want. Today I didn't play my best tennis, and last week I didn't play my best tennis."

The 19-year-old, who defeated newly-installed world number one Serena Williams on the way to reaching the semi-finals of the Australian Open in January, started confidently in front of a sparse Dubai crowd.

She broke in the first set to take a 5-4 lead, but then showed her inexperience, serving a double-fault on set point to allow Cirstea to make it 5-5.

The Floridian - the top ranked teenager - immediately broke again as she went on to claim the first set.

Stephens then took a 3-1 second-set lead, winning nine points in a row, but Cirstea fought back by taking five straight games to square the match.

Cirstea raced through the deciding set in 33 minutes, as the young American's serve collapsed, losing five of her last six service games.

Top seeds Williams and Victoria Azarenka - the world number one and two - are not due on court until Wednesday. Azarenka took three sets to defeat the 15-times Grand Slam winner in Sunday's Qatar Open final.

(Editing by Mark Meadows)