* Djokovic drops a set but goes through
* Serbian feels physically fit after allergy problems
Novak Djokovic feels he is ready to go the distance at the French Open after allergy problems kept the Serbian out of competitive tennis for three weeks.
Djokovic, who overcame a mid-match glitch to launch his French Open campaign with win over Kazakh Evgeny Korolev on Monday, retired because of the allergies from a second-round match at the Belgrade Open on May 3.
He then pulled out of the following week's Madrid Open, raising concerns on his fitness ahead of the claycourt grand slam.
The Serbian third seed, twice a semi-finalist at Roland Garros, won 6-1 3-6 6-1 6-3 as spectators sizzled in 30 degrees of heat on Court Suzanne Lenglen.
"I haven't played a real match since Rome this year, I think. I knew it's gonna be a little bit different feeling stepping on the court and playing a match than practicing in last two weeks," Djokovic, who had last completed a match in a quarter-final defeat against Fernando Verdasco in the Rome Masters last month, told reporters.
"I felt the ball really well in the practice. Right now I feel physically fit and ready to go the distance."
Djokovic steamed through the first set in quick time but went to sleep in the second as his 73rd-ranked opponent briefly threatened the tournament's first major shock.
However, Djokovic quickly recovered his poise and breezed through the next two sets without expending too much more of the energy he will need if he is to challenge for the title.
"I had ups and downs. I didn't play a good second set, but I overcame it," he said.
"From the start of the third set I started playing better, started serving better. It's important. It's going slowly, but I have to be positive about it."
Djokovic will face Kei Nishikori of Japan next.
(Reporting by Martyn Herman; editing by Miles Evans. To query or comment on this story email email@example.com)