John Isner defeated Juan Martin del Potro in three sets on Friday to reach the Paris Masters semi-finals and end the Argentine's chances of qualifying for the ATP Finals.
American world No 14 Isner, who reached the final in Paris last year, surprised the in-form Del Potro 6-4 6-7(5) 6-4 to maintain his own hopes of reaching the season-finale in London, live on Sky Sports.
Isner, who will qualify for London ahead of Pablo Carreno Busta by claiming the Paris title, backed up Thursday's three-set victory over Grigor Dimitrov and impressed on both wings from the back of the court against a subdued Del Potro.
The first set was dominated by serve with both players holding in assured fashion before Isner secured a decisive break in the 10th game of the match to secure the opening set, despite earlier receiving treatment to his ankle.
Both players continued to dominate behind their serve, neither player winning more than two points against the server, with the second set going to a tiebreak, which Del Potro claimed after Isner double-faulted on set point.
Isner, the ninth seed, took control of the third set with a pivotal early break before staying cool under pressure to close out the encounter and leave Del Potro, who had won 20 out of his previous 24 matches prior to the defeat, waving goodbye to his 2017 campaign.
The 32-year-old Isner will meet qualifier Filip Krajinovic in Saturday's semi-finals.
Krajinovic benefited from Rafael Nadal's withdrawal, on Friday, from the tournament through a recurrence of his knee injury, which impacted the Spaniard during his hard-fought three-set victory over Pablo Cuevas on Thursday.
However, Isner is expecting a tough challenge against the Serb: "My opponent came through qualifying so has won five matches already and is playing really well. I just need to play my game and see what happens."
Meanwhile, Julien Benneteau was roared on by a partisan home crowd to reach a maiden semi-final in Paris with a 7-6(5) 7-5 victory over third seed Marin Cilic.
The 35-year-old French veteran, who received a wildcard to take part, has never won a title during his 17-year career on tour but will next face American Jack Sock, who can also qualify for London by claiming the Paris title.
Benneteau, the world No 83, secured a break of serve in Cilic's opening service game before recovering from a 5-2 deficit to take the first set on a tiebreak.
The second set saw both players trade breaks of serve in the early stages before the Frenchman secured the decisive break of serve to close out the match.
Sock recovered from a slow start against Fernando Verdasco to record a 6-7(3) 6-2 6-3 victory, despite losing a closely contested first set on a tiebreak.
However, the world No 22 started strongly in the second set by breaking the 33-year-old Spaniard's first service game to gain control of the set and he maintained his dominance before securing a second break of serve against the increasingly rattled Verdasco to force a final set.
Sock faced a break point in the opening game of the decider but battled through the game before maintaining his momentum by breaking Verdasco's serve straight after.
The 16th seed eventually closed out the contest with a hard-fought service hold to reach the last four in Paris for the first time in his career.
The season-ending extravaganza ATP Finals at London's O2 this November ends another memorable year.
All the action will be covered via our website sky.mnosports.com/tennis with live blogs, reports and expert analysis as the season reaches its climax.
On the move? Head to our app for mobile devices and iPad, or follow our Twitter account @SkySportsTennis to join in the conversation. Who will win the World Tour Finals this year? Have your say...