Daniil Medvedev needed just 56 minutes to subdue Lu 6-2, 6-2, firing nine aces with just one double fault as he advanced to a third-round meeting with Australian Alexei Popyrin.
Alexander Zverev beat Stefanos Tsitsipas 6-4, 7-6 (7/3) in the final of the ATP hardcourt tournament in Acapulco.
Stefanos Tsitsipas and Alexander Zverev will duel for the ATP title in Acapulco, the top two seeds advancing with straight-set semi-final wins.
Australian Open: World No. 1 Novak Djokovic blamed the 14-day quarantine ahead of the tournament for the spate of injuries several players have gone through.
Australian Open: Novak Djokovic showed exemplary determination and strength to beat Alexander Zverev 6-7, 6-2, 6-4, 7-6 on Tuesday to make the semi final.
Australian Open: Novak Djokovic is set to face sixth seed Alexander Zverev in his last-eight clash.
Australian Open: It was the second match in a row where Alexander Zverev has been less than clinical, after he was taken to four sets by 73rd-ranked Marcos Giron in the first round.
Australian Open 2021: Alexander Zverev, a semi-finalist last year who is gunning for a maiden Grand Slam title, lost a tight first set against the 73rd-ranked American before grinding to a 6-7 (8/10), 7-6 (7/5), 6-3, 6-2 win.
Daniil Medvedev battled back from a set down to topple Alexander Zverev and power Russia into the ATP Cup final Saturday.
Alexander Zverev rallied from a set down to beat dangerous Canadian Denis Shapovalov and open his season with a fighting victory in the ATP Cup, while in-form Matteo Berrettini steered Italy into the semi-finals on Wednesday.
Australian Open: Alexander Zverev said that he remained buoyed by his strong showing in the majors last year, which included a semi-final finish at the Australian Open.
Tennis 2020: The year was mostly about coronavirus, though Rafael Nadal did well, while Novak Djokovic would rather forget it.
Several major American sports have a policy setting out a procedure to be followed in such situations, and Novak Djokovic believes tennis should go down the same route.
Novak Djokovic out-battled Alexander Zverev to qualify for the last four at the ATP Finals on Friday, staying on track to match Roger Federer's record of six titles at the end-of-season event.
Daniil Medvedev shocked Novak Djokovic in straight sets to book a place in the last four at the ATP Finals on Wednesday
Alexander Zverev beat Diego Schwartzman 6-3, 4-6, 6-3 on Wednesday to keep alive his hopes of another ATP Finals triumph in London.
Former junior player Olga Sharypova said in a social media post last month that the German world number seven had tried to "strangle" her while at last year's US Open.
Third seed Daniil Medvedev claimed his first Paris Masters title at Bercy Arena on Sunday by battling back from a set down to beat Germany's Alexander Zverev.