John Isner has progressed into the second round of the Monte Carlo Masters after beating fellow American Steve Johnson in straight sets this afternoon.

Isner defeated his compatriot 6-4 6-4 in 71 minutes to seal a first-round win for the first time in the Principality.

Both players recorded a break of serve early on as the pair shared two games apiece in a promising start to the contest.

Johnson's service game was crucially broken again in the fifth game, and it proved decisive as Isner established the cushion needed to clinch a first-set advantage.

Isner, rated 19th in the ATP rankings, broke the world number 51 once more in the first game of the second set in what proved the last break of serve as the pre-match favourite comfortably advanced.