Novak Djokovic has admitted that he struggled to maintain his composure during his French Open semi-final win over Ernests Gulbis.

The former world number one lost the third set on the clay court but eventually managed to come through 6-3 6-3 3-6 6-3 to grab victory and reach his 13th Grand Slam final.

"The first two sets were very good for me and then he started to play with fewer errors," said Djokovic on court after the match.

"It was very difficult to maintain my concentration because the conditions were difficult for me, but I'm very happy to have made it into the final."

The Serbian will play the winner of the second semi-final between Andy Murray and Rafael Nadal.