World number one Jannik Sinner will face Daniil Medvedev in the Shanghai Masters quarter-finals after both had straight-set victories on Wednesday

World number one Jannik Sinner will face Daniil Medvedev in the Shanghai Masters quarter-finals after both had straight-set victories on Wednesday. 

Sinner put some old demons to rest in overcoming American Ben Shelton 6-4, 7-6 (7/1), while Medvedev took out Greece's Stefanos Tsitsipas 7-6 (7/3), 6-3. 

Carlos Alcaraz and Novak Djokovic also progressed to the next round after comfortable wins.

But world number three Alexander Zverev is out after losing to 66th ranked David Goffin 6-4, 7-5.

Shelton, ranked 16, knocked Sinner out at the same stage last year but the Italian looked confident from the start and won in 88 minutes. 

The US Open champion pulled ahead in the ninth game of the first set, breaking when Shelton hit long, then dominated the second set tiebreak.  

World number five Medvedev and Tsitsipas were meeting for the 14th time. 

The Greek started the second set strong, breaking in the first game, but Medvedev broke in the fourth and eighth to claim victory. 

Medvedev and Sinner have already met four times in the final stages of tournaments this year. 

Sinner beat Medvedev in the semi-finals in Miami, the quarter-finals of the US Open and in the Australian Open final, but the Russian ended the Italian's hopes in the last eight at Wimbledon in an epic five-set battle. 

"I'm gonna bring the fight," Medvedev said.

"I could have done much better in the US Open I didn't explore enough my potential during this match. So I'm going to try to explore this potential tomorrow," he said.

Sinner said "We know each other quite well now, we know exactly what to expect, more or less."

"Of course, it's going to be a very tough match, physical match, mental match, and also tactical, so let's see what's coming."

Alcaraz downs Monfils
World number two Alcaraz, who beat Sinner in the China Open final a week ago, downed veteran Gael Monfils 6-4, 7-5 for a 12th straight victory. 

The 38-year-old Frenchman upset Alcaraz at their last meeting in Cincinnati in August and the Spaniard admitted that "was on his mind", saying he was glad he had "stayed calm".  

Alcaraz's quarter-final opponent is 23-year-old Tomas Machac, who beat 13th-ranked Tommy Paul 3-6, 6-4, 6-3. 

"He has really great tennis. He's so, so fast as well, so I have to be focused on that," Alcaraz said of the Czech. 

Machac's teenage compatriot Jakub Mensik burnished his record against top 10 players, overpowering Bulgarian Grigor Dimitrov 6-3, 3-6, 6-4 just days after sending world number six Andrey Rublev home.

Mensik's next challenge is Djokovic after the Serb finished off Russian Roman Safiullin 6-3, 6-2 in 73 minutes.

The former world number one said he had a "great relationship" off the court with Mensik's family.

"I always believed that he's got the potential to be one of the top players in the world and he's building that kind of momentum right now," the 37-year-old said.

He has previously played practice sets with the 19-year-old.

"He got bigger and stronger. So, yeah, it's going to be fun," Djokovic grinned, anticipating a "tough challenge".

Zverev out
The last match of the day saw the tournament lose its second seed with Zverev's straight-set defeat.

Goffin broke first and kept the pressure up.

An increasingly miserable-looking Zverev mounted a second set revival, but couldn't quite close the gap as the 33-year-old Belgian persevered.

"I had nothing to lose, but (Zverev) is always tough to play," said an emotional Goffin, who said he had decided to mount a career revival a few months ago. 

"It was a great feeling I didn't expect to be that offensive, that relaxed on that court."

Goffin will next face the United States' Taylor Fritz, who took less than an hour to demolish 14th-ranked Holger Rune 6-1, 6-2.