Alexander Zverev roared into his second grand slam final by beating Casper Ruud 2-6 6-2 6-4 6-2 at the French Open, the Norwegian affected by illness as he wilted on Court Philippe-Chatrier.

Ruud entered Friday's semi-final rested after benefitting from Novak Djokovic's withdrawal in the last eight, and he controlled the baseline rallies with confidence as he took the opener.

However, a long forehand gifted Zverev a break in the opening game of the second set and the German did not look back from there, winning 92 per cent of points behind his first serve as he levelled things up.

More mistakes crept into Ruud's game and he told the umpire he was feeling unwell three games into the third, when Zverev continued to press home his physical advantage.

Ruud left the court after going 2-1 down in a bid to recompose himself, but Zverev set the tone for another dominant set by crashing home a big forehand winner for an opening-game break, and Ruud never looked like hitting back as the big-serving German advanced. 

Data Debrief: Zverev's clay form rewarded

Zverev has become increasingly comfortable on the clay this year, winning the Italian Open and reaching his first final at Roland Garros.

He is just the fifth player in the last two decades to reach the men's singles final at both events in the same year, after Andy Murray, Novak Djokovic, Rafael Nadal and Roger Federer.

He will take on Carlos Alcaraz in Sunday's showpiece match, having won five of his nine tour-level meetings with the Spaniard.