Daniil Medvedev powered into the US Open semi-finals with a straight-sets win over fellow Russian Andrey Rublev on Wednesday.
The 2019 finalist had won their previous two ATP Tour contests and played the key moments better as he claimed a 7-6 (8-6) 6-3 7-6 (7-5) victory.
It was a match of fine margins despite the one-sided scoreline, with Medvedev claiming the only break of serve midway through the second set after having snatched the first from Rublev's grasp.
The 24-year-old began to struggle physically in the closing stages and roared with delight and relief when he closed out the win and set up a semi-final against Dominic Thiem or Alex de Minaur.
There was scarcely a sniff of a break in the opening set as each man found early rhythm from the baseline, even after the action was briefly suspended due to a power outage.
Rublev seized the initiative in the breaker but squandered three set points at 6-3 up to lose both the opener and his cool, the world number 14 smashing his racquet into the court and his bench in anger.
Medvedev went into the contest having never dropped a set in previous meetings with his compatriot, and the match was firmly under his control when he held to love twice in a row before breaking in the sixth game of the second set with an authoritative smash.
Rublev was looking forlornly for a solution against the Medvedev serve and forehand, the third seed closing out another routine service game to move into a 2-0 lead.
A terrific drop shot seemed to give Rublev renewed vigour early in the third and there was a scare for Medvedev at 4-5 when he needed treatment for a shoulder problem and cramp, although a missile of a cross-court backhand in the next game seemed to dispel some of the concerns.
Rublev successfully challenged a second serve at 1-0 in the tie-break, but he was less fortunate when a thumping Medvedev backhand clipped the outside of the line.
Medvedev was by now clearly hampered physically, choosing to serve and volley at 5-4 ahead for the first time in the match only to drop a routine effort in the tramlines.
But he made certain there would be no threat of a fightback, taking his first match point when Rublev sent a backhand long.
Medvedev  bt Rublev  7-6 (8-6) 6-3 7-6 (7-5)
Medvedev – 50/37
Rublev – 22/17
Rublev – 10/1
BREAK POINTS WON
Medvedev – 1/1
Rublev – 0/0
FIRST SERVE PERCENTAGE
Medvedev – 59
Rublev – 51
PERCENTAGE OF POINTS WON ON FIRST/SECOND SERVE
Medvedev – 89/65
Rublev – 80/61
Medvedev – 106
Rublev – 90