WHAT HAPPENED: As break-point chances go, so goes Rafa Nadal in this US Open.
In his previous match against Leonardo Mayer, the Spaniard squandered 13 break opportunities before finally converting on one, deep in the second set. Nadal grew visibly frustrated by his inability to break.
On Monday afternoon under brilliant sunshine, Nadal appeared dead set on expending less energy, both physical and nervous, to get those crucial breaks of serve.
Against the dangerous Alexander Dolgopolov of Ukraine, the top seed capitalized early in the first set; when he needed to in the second; and immediately in the third and final set. That was exactly what Nadal needed to get his confidence soaring and launch his game into full flight.
Nadal put his previous returning woes to rest and won what might have been a tricky match in convincing fashion, 6-2, 6-4, 6-1, to advance to the quarterfinals.
Nadal not only returned serve well; he pretty much did everything well in crushing Dolgopolov, who had turned in some excellent tennis in reaching the fourth round here. Nadal won buckets of free points with his serve, which he pinpointed well to Dolgopolov's body; he struck his forehand with conviction, deep and close to the sidelines; and he patiently opened the court and found opportune moments to go for winners.
The slight Ukrainian, listed at just 157 pounds, has unexpected pop on his serve and ground strokes to go with his abundant variety of spins and pace of shot. If Nadal were experiencing timing issues, Dolgopolov would be a complicated player to meet.
But Nadal played an extremely clean match, easily his best of the tournament. The world No. 1 won 82 percent of his first-serve points (and a remarkable 79 percent of his second serves), had just 11 unforced errors against 23 winners and did not surrender a single break point.
"I played a solid match; I played with not many mistakes," said Nadal.
"Dolgopolov is a player who can play amazing shots, but sometimes he is a little bit unpredictable. I tried to be very focused with my serve and wait for the opportunities."
Nadal broke Dolgopolov's serve in the final set for the sixth time, racing to an unusually quick, one-hour, 41-minute victory.
WHAT IT MEANS: Nadal is back in a US Open quarterfinals for the first time since 2013, the last time he won this major.
Dolgopolov, ranked No. 64 in the world, has been as high as number 13. The Ukrainian had won two of his last three matches against Nadal, including the hard courts of Indian Wells in 2014. Dolgo was seeking the second major quarterfinal of his career, after last getting that far at the Australian Open back in 2011.
MATCH POINT: Nadal appears to have gotten his game -- and especially his return of serve and offensive forehand -- back on track with this convincing performance. The Spaniard will meet the 19-year-old Russian Andrey Rublev, playing in just his fifth major (the Russian had never previously advanced beyond the second round). Nadal doesn't want to talk about it, but he is just one match away from a potential semifinal meeting with Roger Federer, in what would be the two legends' first encounter at the US Open.