World number one Carlos Alcaraz fended off in-form American Tommy Paul 7-6(6) 6-7(0) 6-3 to reach the Cincinnati Open quarter-finals on Thursday as other top seeds Daniil Medvedev and Greek Stefanos Tsitsipas were sent packing.

Alcaraz had not looked like himself in an uneven third-round performance on Tuesday but was firing on all cylinders on Thursday as he harnessed his mighty forehand to chip away at Paul's defenses in the rain-interrupted battle.
Paul cracked the code to beat the 20-year-old Spaniard earlier this month in Toronto but a handful more errors from the 14th seed this time around helped Alcaraz get the upper hand.
"It was a really tough match," Alcaraz said in televised remarks. "Really, really happy with the level and think I'm getting better and better."
Down a break in the ninth game, Alcaraz found another gear and converted on a breakpoint chance to level the affair.
But he could not take advantage of a 40-to-love head start in the 11th, as Paul proved the ultimate escape artist and closed out the game with a pair of unreturnable serves.
Alcaraz was lethal at the net in the tiebreak and closed out the set with a well-placed slice and a powerful forehand shot that Paul was unable to control.
Paul briefly retook the momentum when he converted on a breakpoint chance in the third game of the second set but frittered away the advantage when he handed Alcaraz a breakpoint with a double fault in the fourth.
They traded breaks twice more before Paul won an epic, nine-deuce 12th game, saving match point three times to stay alive and then sweeping the second-set tiebreak.
But Paul sent one past the baseline to give Alcaraz the break in the opening game of the final set, where he was unable to set up a single break point chance.
Alcaraz broke Paul's serve again in the final game of the match to set up a meeting with Australian Max Purcell, who beat three-time Grand Slam winner Stan Wawrinka 6-4 6-2.
Elsewhere in the day's action, Alexander Zverev upset third seed, Medvedev, 6-4 5-7 6-4 in a clash between former champions.
Zverev, who came into the match with a 6-9 record versus Medvedev and having lost all three of their meetings this year, broke the Russian three times and saved six of eight break points to seal victory in two hours and 32 minutes.
"Very difficult conditions but also a very difficult opponent," German 16th seed Zverev said in his on-court interview. "He is somebody that gives you absolutely nothing. You have to win the match yourself and that's what I did today and I am pleased with that."
Medvedev double-faulted to hand an early 4-3 lead to Zverev and had a glorious chance to get the match back on serve in the next game when he led 40-0 but came up short as the German held before taking the opening set.
Medvedev moved ahead in the second when Zverev pulled a forehand wide to hand over a break and 4-2 lead but the German broke back immediately before the world number three dealt a crushing blow with a break to love to force a decider.
There was little to separate the players in the third set, which was deadlocked at 4-4 when Zverev set up a break point opportunity with a supreme dipping crosscourt forehand winner that Medvedev followed up with a double fault.
Zverev seized his opportunity and sealed the high-quality encounter on his first match point when Medvedev sent a service return long.
Poland's unseeded Hubert Hurkacz unleashed 11 aces and 27 winners to cruise past Tsitsipas 6-3 6-4 in a brisk 1 hour and 5 minutes, setting up a meeting with Australian lucky loser Alexei Popyrin, who defeated Finland's Emil Ruusuvuori 6-2 1-6 6-3.
Hurkacz had not beaten a top-10 opponent this year but wasted no time getting the edge on Tsitsipas, breaking the Greek in the second game before fending off a pair of break-point chances in the seventh game.
He kept the momentum going in the second set, where he immediately broke Tsitsipas, as the Greek was never able to set up a break point chance of his own.
Hurkacz, who won 85 percent of his first-serve points across the entire match, sealed the affair with an ace and a satisfied pump of his fist on Center Court.
Novak Djokovic will cap the evening session when he plays Frenchman Gael Monfils.