World number one Jannik Sinner made it two wins out of two at the ATP Finals as he fought off Taylor Fritz in a high-octane clash inside the Inalpi Arena on Tuesday.
In a repeat of September's US Open final, home favourite Sinner delighted a raucous crowd with a 6-4 6-4 victory in the best match of the tournament so far.
American world number five Fritz went toe-to-toe with Sinner throughout a contest ultimately decided by slender margins with one break of serve in each set.
Sinner made the decisive break in the opening set when Fritz served at 4-5, bringing up a set point with a disguised drop shot and then converting at the first opportunity.
Fritz refused to go away in the second set and had a glimpse of a chance at 3-3 when Sinner fell 0-30 down on serve. Sinner averted that danger though with some fearless tennis and then exerted the pressure when Fritz served to stay in the match, clinching victory in one hour 40 minutes.
Sinner, bidding to become the first Italian to win the prestigious year-ending tournament having reached the final last year, tops the Ilie Nastase Group with two straight sets wins and looks odds on to reach the semi-finals.
Fritz is tied on one win with Russian Daniil Medvedev who earlier beat Australian debutant Alex de Minaur to keep himself in contention for a semi-final spot.
"It was a very tough match, we both knew exactly what to expect," Sinner said after his 67th victory of the season.
"He was very aggressive. I managed to serve very well in the crucial moments. I'm happy how I handled the tough situations like at 3-3 in the second set when the momentum could have changed if he had broken me."
Fritz will be hopeful of beating De Minaur in his last group match to reach the semi-finals although world number four Medvedev, the 2020 champion, has it all to do against Sinner.
Medvedev (above) said he was ready to pack his bags after losing to Fritz on Sunday, but produced a serving masterclass to overpower De Minaur 6-2 6-4.
The Russian's tennis and attitude on Tuesday was in stark contrast to Sunday when he looked distracted and disinterested and earned a penalty point for smashing a courtside microphone.
This time he was fully focussed on the job in hand as he made only 10 unforced errors and conceded only nine points on his serve as he extended his record over De Minaur to 7-3.
Medvedev (below) had been booed by fans during his opening loss and celebrated beating De Minaur by putting his fingers in his ears.
"I went into this match blocking the noise, even from myself," Medvedev said. "I really didn't care what was happening on the court, I just tried to play, and it was a good feeling.
"The more popular you become, the more fans you get, the more haters you get, the more attention you get. Sometimes even the good noise can make you off balance."
Medvedev also suggested that the ATP Tour calendar needs to be refocused around the Grand Slams and Masters 1000 events with the lower-tier ATP 250 tournaments moved to an optional slot later in the year.
Several players have voiced concerns over the calendar, with four-times Grand Slam winner Carlos Alcaraz saying the tight schedule makes it difficult to stay motivated throughout the year and increases the risk of injuries.
From next season, seven of the nine ATP Masters 1000 events will be held across 12 days, a decision which was criticised by Stefanos Tsitsipas last week.
"This year I only tried to play big tournaments," Medvedev said.
"I think there should be more bigger, important tournaments, which should be like, 'Okay, these are the tournaments where we define who is going to be top 10, like Masters 1000.'
"You play good in them, you will be there. The schedule should somehow be around them."
Medvedev suggested staging the top tournaments earlier in the year, adding: "Then you put all the 250s after for people that want to continue playing.
"If you're good enough, you finish the season in whatever, October, play in Masters. Doesn't matter. Don't count the tournaments after. If you still feel like you need more points for Australian Open or more matches, you do it after."
World number three Carlos Alcaraz is unlikely to be at his best for Wednesday's ATP Finals match against Andrey Rublev as the four-times Grand Slam champion continues to struggle with illness, the Spaniard's coach Juan Carlos Ferrero said.
An off-colour Alcaraz lost 6-1 7-5 to Norway's Casper Ruud in his opening match on Monday and the 21-year-old cancelled a public training session on Tuesday.
"As soon as he moves a little, it's hard for him to breathe. His chest is a bit tight. It's a bad time to get sick," Ferrero said.
"We should not anticipate whether or not he will play tomorrow. We have all played in these circumstances. I don't think he's going to be so bad that he won't be able to play. It's going to be difficult for him to be 100% tomorrow.
"Rublev is a player who moves a lot, you have to be very good on your legs and, right now, that's what's costing him a little more, recovering between points... "
Alcaraz won the Beijing title in October but his form since winning Wimbledon earlier this year has been unconvincing, suffering a second-round exit at the US Open and being beaten by Ugo Humbert in the round of 16 at the Paris Masters.
After taking on Rublev later on Wednesday, he faces world number two Alexander Zverev in his final round-robin match of the eight-man event.
Alcaraz reached the semi-finals of the ATP Finals last year, where he was beaten by eventual winner Novak Djokovic.
