Novak Djokovic dropped his first set of the Italian Open but recovered to beat qualifier Dominik Koepfer and reach the semi-finals in Rome.

The omens were certainly not good for German Koepfer when he lost the first four games of the match, but he responded by breaking Djokovic twice in a row to serve notice that this might not be a straightforward afternoon for the world number one.

Djokovic moved 3-1 ahead in the second set but smashed his racket to the court after dropping serve in the next game.

Koepfer capitalised to level the match but Djokovic kept his cool and eventually came through 6-3 4-6 6-3 to set up a clash with Norwegian Casper Ruud.

There will inevitably be heightened attention on Djokovic’s behaviour on-court following his US Open default, and he said of his loss of composure against Koepfer: “Let me tell you that it’s not the first nor the last racket that I’ll break in my career.

“I have done it before. I’ll probably do it again. I don’t want to do it, but when it comes, it happens. That’s how I release sometimes my anger.

“And it’s definitely not the best message out there, especially for the young tennis players looking at me. I don’t encourage that, definitely. But, look, we’re all people. We all do our best.”

It will be Djokovic’s 69th semi-final at Masters level and 11th in Rome alone, but this is new territory for Ruud.

The 21-year-old became the first Norwegian player to make the semi-finals at this level with a 4-6 6-3 7-6 (5) victory over Italian number one Matteo Berrettini.

Ruud said: “This is my first time in the semi-finals, and today was even my first time in the quarter-finals. I’m just enjoying the moment. I’m in a good flow. I have gained good confidence in my game this week.

“I have just been motivated and pumped up for the clay to start again, and it’s a different time than what it usually is, but it’s still the same beautiful place, same beautiful venue and beautiful city.”