World number one Novak Djokovic was surprisingly beaten by unseeded Kei Nishikori of Japan in the semifinals of the Basel Open on Saturday, suffering a new injury setback in the process.
The Serb, returning to action this week for the first time since aggravating a back injury in the Davis Cup tie against Argentina in mid-September, was troubled by his shoulder as he lost for only the fourth time on the ATP circuit this year.
Nishikori's final opponent will be Roger Federer, who continued his dominance over his fellow Swiss Stanislas Wawrinka with a straight sets win in Saturday's other semifinal.
Nishikori, a wildcard entrant, romped through the final set as Djokovic, who received treatment on his shoulder between games, lost heart, winning 2-6 7-6 6-0.
"Recovering is what matters now," said Djokovic, who is due to play in Paris next week.
"I don't think in these conditions I will be able to train for the next couple of days. I'll see what the team think."
Djokovic, the reigning Australian Open, Wimbledon and US Open champion, came onto court for his first match last Tuesday wearing a halloween mask, but was not in the mood for joking after Saturday's exit.
"It's tennis, sometimes you lose these matches. I have to give my opponent credit, he was better than me, but I didn't take my chances," said Djokovic, who has reached the semi-finals in all 13 ATP tournaments in which he has competed this year.
"He didn't make any mistakes and he was getting some impossible balls back.
"I wanted to get a couple of matches under my belt; unfortunately I got another injury."
Djokovic admitted his back injury had been on his mind all week as he dropped sets in two of his first three matches.
"Competition is different to practice. I have carried it from the U.S. Open and I am still afraid something is going to happen," he said.
Djovkovic had little trouble in rattling off the first set but was already receiving massage on his shoulder and arm.
Both players broke once in the second set but 21-year-old Nishikori, ranked 32, took control in the tiebreak and never looked back.
The wild card entrant broke in the second game of the third set and, by the fourth, Djokovic looked beaten.
He misjudged a Nishikori forehand, letting it go only to see it land in, and after more unforced errors produced a wild forehand to present his opponent with another break.
By this time he clearly wanted to get it over with and was first onto court after the next break, putting himself out of his misery by hitting another wayward forehand.
In the second match, world number four Federer won 7-6 6-2 to record his 10th win in nine meetings against Wawrinka. Federer, playing in his first tournament since the US Open, will attempt to win only his second title of the season following Doha in January.