Australian Open overnight: Djokovic into semis again, Serena to meet Osaka

The first Grand Slam of 2021 is in full swing. Each morning, we'll review the action you may have missed Down Under. Here's what happened overnight on Day 9 of the Australian Open.

Top story: Another showdown for Serena, Osaka

Serena Williams has returned to the Australian Open semifinals for the first time since she won the tournament in 2017.

Williams claimed the last five games and beat No. 2 seed Simona Halep 6-3, 6-3 in the quarterfinals despite 33 unforced errors. She set up a showdown with Naomi Osaka for a spot in the final.

Williams is seeking a record-tying 24th major singles championship.

She was terrific in the first set against Halep but had a bit of a wobble early in the second and trailed 3-1.

Williams turned things back around and let out a big smile when her forehand winner ended the victory.

Three-time Grand Slam champion Osaka advanced to the semifinals by overpowering Hsieh Su-wei 6-2, 6-2.

Against Hsieh, Osaka hit seven aces, lost only two points on her first serve and was never broken.

Osaka has won 19 consecutive matches, a streak that includes a U.S. Open title in September. The streak also includes Osaka’s fourth-round win last week, when she saved two match points and swept the final four games to overtake Garbine Muguruza.

Nole into Aussie Open semis for 9th time

Defending champion Novak Djokovic beat sixth-seeded Alexander Zverev 6-7 (6), 6-2, 6-4, 7-6 (6) to reach the Australian Open semifinals for the ninth time.

The top-ranked Djokovic has never lost at Melbourne Park after making it to the last four.

He shattered his racket in the third set by smashing it into the court when he lost a game. But that only seemed to spur a resurgence as he won the next five games to take the set.

Djokovic also had to come back from an early break in the fourth and he saved a set point before forcing a tiebreaker. He closed it out on his second match point with his 23rd ace.

He will next play Aslan Karatsev after the No. 114-ranked Russian qualifier beat Grigor Dimitrov.

Karatsev's magical run continues

Aslan Karatsev has become the first man to reach the semifinals in his Grand Slam debut during the professional era.

The 114th-ranked qualifier from Russia advanced to the final four at the Australian Open with a 2-6, 6-4, 6-1, 6-2 win over 18th-seeded Grigor Dimitrov of Bulgaria

Dimitrov won the opening set easily but looked sluggish in the second and stopped chasing shots in the third.

After that set, Dimitrov was visited by a trainer and then took a medical timeout for treatment on a muscle problem around his hip or back.

He returned for the fourth set but couldn't compete.

Dimitrov hadn't dropped a set in his first four matches. Karatsev was coming off his first-ever five-setter after coming back from two sets down to beat No. 20 Felix Auger-Aliassime. He beat eighth-seeded Diego Schwartzman in straight sets for his first win over a Top 10 player.