After two days of world-class action at the Nitto ATP Finals, each of the eight singles players and eight doubles teams has played one match in Turin. While those who won their openers could seal a semi-final place on Tuesday, others are bidding to keep their hopes of progress alive by avoiding an 0-2 start.
Opponents Rafael Nadal and Felix Auger-Aliassime fall into the latter category on Day 3, while Casper Ruud and Taylor Fritz will look to stay perfect on the week in their evening matchup.
In doubles action, Marcelo Arevalo and Jean-Julien Rojer face Marcel Granollers and Horacio Zeballos with both teams in search of their first victories. Rajeev Ram and Joe Salisbury meet Lloyd Glasspool and Harri Heliovaara in a battle of 1-0 duos.
 Rafael Nadal (ESP) vs.  Felix Auger-Aliassime (CAN)
Nadal and Auger-Aliassime took very different paths to Turin in the past two months. While Nadal played just one singles match following the US Open — a Rolex Paris Masters defeat against Tommy Paul — Auger-Aliassime put together a career-best 16-match win streak as he claimed titles in Florence, Antwerp and Basel before reaching the Paris semi-finals.
But the Canadian has now dropped two matches in a row, his Bercy defeat against Holger Rune followed by another loss to Ruud in the 22-year-old's Nitto ATP Finals debut. But the unique format at the season finale means there is still time to make amends.
“My back is against the wall,” Auger-Aliassime said after his 7-6(4), 6-4 defeat to Ruud . “It would have been better to start with a win here... I need to bounce back and play better, play a little bit better. I'm not far from playing well, but there are a few things I can do better.”
The fifth seed will need to earn his first ATP Head2Head win in three tries against Nadal to have a realistic chance of advancing to the Turin semi-finals.
Nadal struggled to find his best form in a 7-6(3), 6-1 defeat to Fritz on Sunday and has now lost his past three matches, all against American opposition. Nadal said he found himself on defence in the majority of the points against the powerful American, and the 36-year-old will be expecting a similarly aggressive approach from Auger-Aliassime.
“Serving like Fritz served, then you are under pressure all the time," Nadal said, noting how the speed of the indoor court robbed him of the time he needed to play on his terms. "When somebody is serving that way, on the return he is going for every shot. [It was] just well played from him, not enough from me.”
Auger-Aliassime nearly hit his way to a victory when he met Nadal at Roland Garros earlier this season, but the Spaniard did just enough to escape in five sets.
Will the change of surface help the Canadian change the outcome in Turin, or will Nadal get back on track in his bid to win the Nitto ATP Finals for the first time? If the Spaniard can claim the elusive title, he would also snatch the year-end No. 1 Pepperstone ATP Ranking from the injured Carlos Alcaraz.
 Casper Ruud (NOR) vs.  Taylor Fritz (USA)
Even with their twin 1-0 records, Ruud and Fritz will remain on high alert, knowing there is little room for error at the Nitto ATP Finals.
Ruud was very happy with his win against Auger-Aliassime after a difficult few months following his run to the US Open final, which lifted him to a career-high Pepperstone ATP Ranking of World No. 2.
“I’m not going to try to relax, but I know that I don’t need to sort of stress or try to rush things to try to turn it around, so that’s hopefully a good thing," he said post-match. "I’m not going to count on anything, I’m just going to focus on the next two matches and in a way pretend that this never happened. So, I need to bring my 'A' game in the next two matches as well.”
While Ruud and Fritz will be contesting their first ATP Head2Head meeting, the Norwegian faced a similarly attack-minded opponent in Auger-Aliassime on Sunday. While Fritz and Auger-Aliassime are from from the same player, both base their games around big serves and big forehands — weapons which free them up to take chances on return.
From Fritz's perspective, he faces a second consecutive opponent whose favourite surface is clay, following his win against Nadal. Against the Spaniard, the American felt the quick conditions at the Pala Alpitour benefitted him both on serve and in the rallies.
"The court's definitely fast. For me, fast is good for my serve, it's good for my backhand," he explained in his on-court interview. "I feel like different speeds always have parts that help my game, and parts that hurt my game. On a slower court, I have so much more time to kind of load up on a forehand.
"On a court like this, I can lean into my backhand and hit it deep cross to Rafa's forehand, and it makes it a bit tougher for him to step in and crush it. On a slower surface, he gets time on the forehand when I go backhand cross, and it's probably done for me. So I'd say that's where it helps me the most on the ground against him."
While he was able to stay neutral in the rallies with his backhand, it was the Fritz forehand which did the heavy lifting off the ground against Nadal. This was quantified by his 8.9 INSIGHTS Shot Quality score, which factors in a range of metrics to determine the effectiveness of a given stroke. After hitting 30 per cent of his shots In Attack against Nadal, according to INSIGHTS, Fritz will again hope to keep Ruud pinned back on Monday.
Roland Garros champions Arevalo and Rojer meet Granollers and Zeballos for the first time on Tuesday in Turin, with both pairs looking to rebound from Day 1 defeats. While Arevalo and Rojer are seeking their first Nitto ATP Finals win in their tournament debut as a pair, Granollers and Zeballos are bidding for a third straight semi-final at the season finale. Spain's Granollers also won the 2012 year-end title alongside countryman Marc Lopez.
Returning finalists Ram and Salisbury won perhaps the most dramatic doubles match of the tournament against Granollers/Zeballos, earning a 6-3, 6-7(8), 10-8 victory after letting slip set points in the second set. Thy face group leaders Glasspool and Heliovaara, the only team yet to drop a set in Turin. The British-Finnish duo edged Arevalo/Rojer 7-5, 7-6(3) on Sunday.