Rafael Nadal saved a match point and rallied from two service breaks down in the third set to edge Russia's Daniil Medvedev 6-7 (3-7), 6-3, 7-6 (7-4) and record his first victory at this year's ATP Finals.
The world No. 1 is known for his indomitable fighting spirit, but even he looked deflated in this round-robin contest when he went down 5-1 in the deciding set against an opponent who had all the answers in their lengthy baseline rallies.
The Spaniard, however, got a new lease on life by saving a match point in the seventh game en route to holding serve and then breaking Medvedev's serve in the ensuing game to make the score 5-3 late on Wednesday, reports Efe news.
He later created three break points with Medvedev serving at 5-4 and managed to convert the third one when the Russian was unable to execute an attempted drop volley on the full stretch.
After a pair of service holds the match came down to one final tiebreaker that Nadal won thanks to consecutive unforced errors by his opponent on the final two points, the last of which was awarded to the Spaniard after a Hawk-Eye challenge.
Medvedev came out on fire in the opening set, surrendering just six points on serve, throwing down seven of his 21 overall aces and not facing a single break point.
Nadal, for his part, got into trouble in one game but managed to stave off the lone break-point opportunity he faced.
In the tiebreaker, Medvedev took a 6-3 lead when Nadal dumped a forehand in the net and then clinched the opening set with yet another unreturnable serve.
Although Nadal was struggling to get enough height on the ball in the rallies to bother his 1.98-meter (6-foot-6) opponent, he finally got into a Medvedev service game at the start of the second set and managed to secure the first service break of the match.
The Spaniard then remained rock-solid on serve the rest of the set and evened the match at a set apiece with a second service break.
But the momentum shifted abruptly at the start of the third set when Nadal, seemingly frustrated at his inability to put Medvedev under pressure from the baseline, made a couple of loose errors to drop his serve for the first time.
The Spaniard then appeared confused and discouraged as Medvedev stretched his lead to a commanding 5-1 with four service holds and another service break, but the world No. 1 showcased his legendary competitive drive yet again by winning six of the final seven games