PIX: Djokovic cruises; Alcaraz holds off Paul

Novak Djokovic cruised past Gael Monfils and Carlos Alcaraz fended off in-form American Tommy Paul to reach the Cincinnati Open quarter-finals on Thursday while other top seeds Daniil Medvedev and Stefanos Tsitsipas were sent packing.

Djokovic, twice a winner in Cincinnati, dominated the baseline rallies in his 6-3, 6-2 win over Monfils and extended his perfect record against the Frenchman to 19-0 -- the most lopsided unbeaten ATP head-to-head record in the Open Era.

The Serbian made the most of a loose service game from Monfils and broke to love at 5-3 in the first set to close it out.

After racing to a 5-0 lead in the second he faltered on his first attempt to serve it out, but completed the win two games later in an hour and eight minutes. Djokovic will next face home favorite Taylor Fritz.

"We've been playing each other in different parts of the world, also in juniors," Djokovic said. "Early on, I struggled with him physically.

"We haven't played for quite a few years. It's great to see him back playing at a high level."

World number one 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 earlier this month in Toronto but a handful more errors from the 14th seed this time around helped Alcaraz get the upper hand in his 7-6(6) 6-7(0) 6-3 victory.

"It was a really tough match," Alcaraz said. "Really, really happy with the level and think I'm getting better and better."

Alcaraz came back from a break down four times in the first two sets but squandered three match points in the second.

The Spaniard was serving at 4-3 and up a break in the decider when rain stopped play for over an hour. He broke Paul's serve again in the final game of the match to book a quarter-final clash with Australian Max Purcell.

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% 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.