World No. 1 Carlos Alcaraz sailed into the Paris Masters third round with a 6-4, 6-4 win over Yoshihito Nishioka but Rafael Nadal and Daniil Medvedev both slumped to surprise losses on Wednesday.

Alcaraz was quick out of the blocks and struck 30 winners to overpower his Japanese opponent despite losing serve in the first set on the only break point he faced all match.

Nadal won the first set against American Tommy Paul but went down 3-6, 7-6(4), 6-1. Meanwhile, world No. 3 Medvedev, who won the Vienna title last week, lost 6-4, 2-6, 7-5 to Australian Alex de Minaur.

The defeat ended 22-time Grand Slam champion Nadal's hopes of reclaiming the No. 1 ranking from Alcaraz this week. 

He said he does not expect to be in good enough shape to mount a serious challenge at the season-ending ATP Finals, which runs from November 13 to 20 in Turin this year.

Nadal has never won the ATP Tour's finale, though he has reached the final twice.

"For me (it's) difficult to imagine now arriving in the World Tour Finals in enough good shape to win a tournament that I didn't win during all my tennis career."

Earlier, fourth seed Stefanos Tsitsipas produced a fine performance to oust Dan Evans, breaking the Briton early in both sets and making the most of his opponent's unforced errors to secure a 6-3, 6-4 victory.

Canada's Felix Auger-Aliassime and Russian Andrey Rublev sealed the last two places at the ATP finals as Taylor Fritz's hopes vanished with a loss to Gilles Simon. 

Auger-Aliassime battled to a 6-7(6), 6-,4 7-6(6) win over Swede Mikael Ymer while Rublev beat John Isner 6-2, 6-3 on Tuesday.

Other stars of the ATP finals are Alcaraz, Novak Djokovic, Nadal, Casper Ruud, Tsitsipas and Medvedev.

(With input from agencies)