ATP Tour Finals: Fritz meets Novak in semis, Nadal signs off with win

American Taylor Fritz outlasted Felix Auger-Aliassime in three sets and Rafael Nadal avoided matching his worst ever losing sequence with a 7-5, 7-5 victory over Norway's Casper Ruud in round-robin play at the ATP Finals on Thursday.

In a clash of tournament debutantes neither Fritz nor Auger-Aliassime could make inroads on the other's serve but in the first set tiebreaker, the Canadian's normally solid backhand began to misfire and a forehand error put Fritz out ahead.

The players remained on serve in the second to bring about another breaker that Fritz appeared to have in hand while leading 4-2.

But an errant ball toss produced Fritz's first double fault and shifted momentum in favour of Auger-Aliassime, who pumped his fist after slapping a crosscourt winner to force a deciding set.

The key game of the match came with Fritz leading 3-2 in the third when he finally got his first looks at break points, converting his fourth opportunity when Auger-Aliassime pulled a forehand wide.

Fritz rolled from there, holding to love to consolidate the break and jumping in the air when Auger-Aliassime pushed a backhand out on match point, his 36th unforced error.

"It was tough, no one really had any chances early on," Fritz said after his 7-6(4) 6-7(5) 6-2 win.

"I had to just not get frustrated, had to reset. I felt going into the third that a break was coming."

Fritz will face Novak Djokovic in the semi-finals.

Rafael Nadal may be heading home but he made sure he avoided matching his worst ever losing sequence with a 7-5, 7-5 victory over Norway's Casper Ruud at the ATP Finals on Thursday.

Back-to-back straight sets defeats in the Green Group by Taylor Fritz and Felix Auger-Aliassime meant the 22-time Grand slam champion missed out on the semi-finals.

But the Spaniard was clearly eager not to end a season that began in such spectacular fashion by succumbing to a fifth successive defeat -- something the 36-year-old had not experienced since before his career took off in 2004-05.

With world number four Ruud already assured of a semi-final berth the match was in reality a dead rubber.

Even so the first set was full of intensity inside the Pala Alpitour where the afternoon crowd were firmly behind Nadal.

Nadal fought off a couple of break points at 4-4 in the opening set as Ruud threatened but after that the Mallorcan found the range on his forehand.

The 23-year-old Ruud went down 0-40 on serve at 5-6 and world number two Nadal needed just one chance to seal the set, punching away a volley into an empty court.

It was a similar story in the second set with nothing between the players until Nadal pounced again in the 12th game.

Ruud saved one match point but Nadal then clubbed away a backhand winner to finish his season on a high.

"I've been practising well but just not had enough matches to be at the level I need to be, not enough confidence after six tough months," Nadal said on court.

"At least I finished with a positive victory which is important."

Ruud will go on to the semi-finals but is now 0-8 against opponents ranked in the top three.