And he underlined his status as the man to beat in Shanghai as he battered the Italian Fognini 6-3, 6-1.
Del Potro will John Isner of the US or Viktor Troicki of Serbia in the last eight on Friday.
In the quarterfinals, Nadal will play sixth-seeded Grigor Dimitrov of Bulgaria, who got past Sam Querrey of the USA 6-3, 7-6 (3).
Sheriff drives through hellish landscape during California wildfires
Taken as a group, the fires are already among the 10 deadliest in California history, and the death toll is expected to grow. They meshed like gears to pull dry air and high winds into northern California, Anderson said.
However, there is a determined look in the eye of the 29-year-old and a first title of the year would send him soaring up to 12th.
The 46th-ranked Harrison led 4-2 in the third set and then 6-3 in the tiebreaker.
Third seed Zverev was a different matter, though, and, after losing the first four games, Bedene accepted he would not be able to compete and shook hands.
Matt Damon Ruins Chris Hemsworth's 'Kimmel' Interview
The Boston-bred movie star Damon showed up on the air uninvited, as he often does, to jokingly get under Kimmel's skin. You know who else was there? But Damon wasn't going to let Kimmel bump him off his lineup again.
It was del Potro's only break of serve for the match as the world No.23 held strong to close out the match five games later.
A fan at least came away with a demolished racquet for a souvenir after the young German handed it to a spectator.
The 20-year-old Zverev, who has collected 5 ATP World Tour titles this season, lost his temper when broken by the Argentine at 2-2 in the decider and flung his racquet down to the ground, reports Xinhua news agency. "I'm a bit pissed off because I feel like I played well and that's the upsetting part of it - I could have done great in this tournament".
The famous footballer is elected President of Liberia
Weah, standing for the Coalition for Democratic Change, was one of 20 candidates who took part in the election. The Liberian became the only Ballon d'Or victor whose national team never played at the World Cup.
Fourth-seeded Marin Cilic will face Albert Ramos-Vinolas of Spain.