Australian Open 2021: Serena Williams against Simona Halep, Naomi Osaka versus Hsieh Su-wei in quarter-finals

Melbourne: A quick look at the Australian Open: LOOKAHEAD TO TUESDAY Serena Williams goes up against Simona Halep in the quarter-finals — their 12th meeting on tour in a matchup that dates to a decade ago. Williams leads the series 9-2, but Halep won their most recent showdown, 6-2, 6-2 in the 2019 Wimbledon final. That was one of four consecutive defeats in Grand Slam title matches for Williams as she chases her record-tying 24th major singles trophy. Naomi Osaka, whose three major championships include the 2019 Australian Open, goes up against Hsieh Su-wei, who at 35 is the oldest woman to make her Grand Slam quarter-final debut. Hsieh hadn’t won a match against a Top 10 opponent until 2017, but now has seven such victories. Four of their five previous matches have gone three sets; Osaka is 4-1 head-to-head. In the men’s quarter-finals, eight-time Australian Open champion Novak Djokovic carries an abdominal muscle injury into his match against 2020 US Open runner-up Alexander Zverev. Djokovic holds a 5-2 edge over Zverev overall, including winning the last four in a row they’ve played. Djokovic seeks his 31st career appearance in a Grand Slam semi-final as he chases title No 18, which would move him within two of rivals Roger Federer and Rafael Nadal. The other men’s match is 18th-seeded Grigor Dimitrov against 114th-ranked Russian qualifier Aslan Karatsev, who is making his Grand Slam main-draw debut at age 27. TUESDAY’S FORECAST Sunny with cloudy periods, high of 31 degrees Celsius (88 Fahrenheit) MONDAY’S WEATHER Mostly sunny, high of 26 Celsius (79 Fahrenheit). MONDAY’S KEY RESULTS Women’s Fourth Round: No 1 Ash Barty beat Shelby Rogers 6-3, 6-4; Jessica Pegula beat No 5 Elina Svitolina 6-4, 3-6, 6-3; No 22 Jennifer Brady beat No 28 Donna Vekic 6-1, 7-5; No 25 Karolina Muchova beat No 18 Elise Mertens 7-6 (5), 7-5. Men’s Fourth Round: No 2 Rafael Nadal beat No 16 Fabio Fognini 6-3, 6-4, 6-2; No 4 Daniil Medvedev beat Mackenzie McDonald 6-4, 6-2, 6-3; No 7 Andrey Rublev beat No 24 Casper Ruud 6-2, 7-6 (3), 0-0 ret.; No 5 Stefanos Tsitsipas beat No 9 Matteo Berrettini, walkover. STAT OF THE DAY 18: Medvedev’s winning streak. QUOTE OF THE DAY: “It’s definitely one Russian in the semis. Three Russians in the quarters . . . first time in the history. It’s great for our sport,” Medvedev on his country’s success thus far in Melbourne.