Andy Murray and Dan Evans joined Kyle Edmund in the third round of the US Open, making it the first time since 1968 that three British men have gone that far into the tournament.
Second seed Murray won 6-4 6-1 6-4 under the new roof on Arthur Ashe Stadium as a storm hit New York.
Evans beat German Alexander Zverev 6-4 6-4 5-7 6-2 to reach the third round for the first time in three years.
Murray now meets Italian Paolo Lorenzi while Evans faces Stan Wawrinka.
Edmund, 21, reached the third round with a straight-sets win on Wednesday.
Paul Hutchins, Roger Taylor and Peter Curtis were the last three British players to make the third round of the US Open in the same year, in 1968.
Sixth seed Kei Nishikori of Japan beat Russia’s Karen Khachanov 6-4 4-6 6-4 6-3 and Austrian eighth seed Dominic Thiem saw off Ricardas Berankis of Lithuania 6-4 6-3 6-2.
Rio 2016 Olympic finalist and 2009 US Open champion Juan Martin del Potrobeat local favourite Steve Johnson 7-6 (7-5) 6-3 6-2 to reach the third round for the first time since 2012 following a series of injuries.
In the women’s draw, Britain’s Naomi Broady was beaten 7-6 (11-9) 6-3 by fourth seed Agnieszka Radwanska of Poland.
You couldn’t hear the ball – Murray
A flurry of resistance from Granollers at the end of the first set, and a stadium reverberating to the noise of spectators and rain, could not derail Murray.
“You couldn’t really hear the ball, which makes it tricky, but we’re lucky to play under the roof because otherwise there’d be no tennis right now,” said Murray.
The Scot, 29, went through in two hours and 22 minutes to take his record to 24 wins and one defeat since the beginning of Queen’s Club in June.
There were 34 winners but a first-serve percentage of just 43% and 28 unforced errors will give him something to work on before Saturday.
Granollers, ranked 45th, quickly fell 5-2 behind but a shift to more aggressive tactics made Murray work hard to close out the set, the second seed needing 23 minutes and seven set points to clinch the final two games.
Murray also had to see off a couple of break points early in the second set but then eased away with five games in a row for a two-set lead.
The match had begun under the new roof that covers the 23,000-capacity Arthur Ashe Stadium, which has the effect of keeping out the rain but also trapping in the noise of the spectators.
With a torrential downpour beating on the new structure, the second half of the contest was played out amid a persistent buzz of noise, but Murray remained focused and grabbed the decisive break at 4-4 in the third set.
“I hit quite a lot of winners, although first-serve percentage wasn’t great,” Murray said. “I would have liked to make a few more first serves but it is a little bit different serving under the roof, a little heavier conditions.”
Evans matches 2013 achievement
Zverev, one of the brightest teenage prospects in tennis, cut a frustrated figure in the four-set match as Evans beat a top-30 opponent for only the third time.
Having never progressed beyond the third round of a Grand Slam tournament, 26-year-old Evans will now have to overcome two-time Grand Slam champion Wawrinka if he is to make the US Open his best ever tournament.
Birmingham-born Evans, ranked world number 64, is expected to rise into the top 50 after a year where he also reached the third round of Wimbledon – where he was knocked out by Warwinka’s Swiss compatriot, Roger Federer.
“Three years ago, as a qualifier, Evans made a very unlikely appearance in the third round. There is less surprise in New York this year given the dramatic progress he has made and his run to the third round at Wimbledon. He put in a very accomplished performance against the world’s best teenager.
“Zverev was often agitated by line calls that went against him, and on one occasion, smashed his racquet four times into the cement.
“When the two players changed ends, Evans spotted a few tiny fragments of racquet on the court and calmly asked the ball boys to sweep them away.”