Next up, it was Roger Federer who took on Dominic Thiem in a must-win encounter for both, and it was the Swiss who eased passed the error-strewn Austrian in straight, 6-2, 6-3, sets to keep a ideal 16-0 record in second round-robin encounters at the ATP finals.
On Tuesday Night and Just 2 days after a shocking straight-sets defeat against Kei Nishikori of Japan, the 20-time grand slam champ was in good shape and won the first set 6-2.
Nishikori branded his 6-0 6-1 defeat to Kevin Anderson as one of the "worst" of his season, while Anderson hailed the victory as one of the "best" of his career, and the Japanese will be hoping it was just a bad day at the office.
The 37-year-old six-time victor knew anything other than victory would see him fail to qualify for the last four for only the second time in 16 appearances at the O2.
After all the eight players showed their billing in their opening encounters, it was time for things to heat up a little as a semi-final berth and an elimination beckoned on Day 3 of the 2018 Nitto ATP Finals.
He said: "It feels good, I'm very happy I showed a reaction after the last match against Kei". I don't know. But, yeah, I just didn't play well this week. But I asked to play on Monday at the US Open and I played on Tuesday night.
A big key for the Swiss was his play on serve, as he did not face a single break point during the one-hour, seven-minute match and won 86 percent of his first-serve points and 81 percent of his second-serve points.
Federer turned the screws to break again immediately in the second set and never looked in any danger.
Federer grabbed a break in the third game against a nervous-looking Thiem and a second for 5-2 on his way to taking the first set. "I could win and still not make it, so from that standpoint it's not in my power", Federer said.
Federer will likely have to avenge his Wimbledon loss this year to Anderson to reach the semi-finals, although all four players in the group could still mathematically progress.
"He was hitting the ball really well and it was making me impatient".
"That's amongst the matches best I've played", said Anderson.