Novak Djokovic said he could have been a little more efficient as he beat Mats Moraing in Belgrade, but he credited his opponent for that.
Djokovic does not usually play a tournament a week before a Grand Slam, but a delay to the start of Roland Garros gave Belgrade a chance to deliver another event in Serbia this year.
That was too attractive a proposition for Djokovic to miss, and he made a strong start by beating world number 253 Moraing on Tuesday.
It was the first time the pair had played each other, and although the world number one was able to ultimately ease past the German, he was impressed with what he saw.
“It was a very good start," Djokovic said after the match. "I started 6-2 against a player I’ve never faced before. He was going for some shots today that were amazing.
“I was twice a break up in the second set so I maybe could have finished out the job earlier, but credit to him for fighting, for playing really well, for playing very courageous, very bold tennis.”
The result sees Novak Djokovic improve his record this season to 17-3, and moves him level with Guillermo Villas in fifth for all-time ATP wins with 951.
Djokovic will now face Federico Coria, brother of former world number three Guillermo Coria - in the next round.
Why not test your tennis knowledge by tackling one of our fiendish quizzes too?