Novak Djokovic outclassed Lorenzo Musetti to reach the Paris Masters semi-finals after Carlos Alcaraz retired due to an abdominal injury.

Djokovic moved into the last four of a Masters 1000 event for a staggering 74th time with a commanding 6-0 6-3 victory over Musetti on Friday.

The defending champion will do battle with Stefanos Tsitsipas for a place in the final as he eyes a seventh Paris Masters title.

Sixth seed Djokovic made only 10 unforced errors and broke five times, not allowing his Italian opponent to have a game point until early in the second set.

The 21-time grand slam champion only needed 74 minutes to dispatch the unseeded Musetti, moving two victories away from a fifth title of the season.

Meanwhile, world number one Alcaraz's participation in the ATP Finals next week is in doubt after he was injured in his quarter-final against Holger Rune.

Rune won the first set 6-3 and the Dane was 3-1 up in a second-set tie-break when US Open champion Alcaraz brought the match to a premature end.

As Alcaraz prepares to discover whether he can play in the season-ending tournament in Turin, Rune can look forward to facing Felix Auger-Aliassime in his maiden Masters 1000 semi-final.

Auger-Aliassime beat Rune to take the title in Basel last weekend and the Canadian stretched his winning run to 16 matches by beating Frances Tiafoe 6-1 6-4.

Tsitsipas was the last man to seal his place in the semi-finals, getting the better of Tommy Paul, who beat Rafael Nadal earlier in the week, 6-2 6-4.