Briton Kyle Edmund came through a tough test to beat Filip Krajinovic 7-5 6-3 in the Shanghai Masters first round.
Edmund was 4-2 and break point down in the first set when the umpire allowed a late challenge to a line call which went in his favour.
He took the game before levelling at 4-4 and went on to take the opening set.
One break in the eighth game was enough for world number 14 Edmund in the second set as he beat the world number 35 in one hour 31 minutes.