Rafael Nadal beat sixth-seeded Gael Monfils in four sets Monday to reach the quarterfinals of a Grand Slam tournament for the 30th time, prompting talk of a potential Australian Open final against Roger Federer. With top-ranked Andy Murray and No. 2 Novak Djokovic upset in the first week, Raonic, a Wimbledon finalist, is the highest-ranked player in the draw. Nadal, 30, is the only major winner still in contention on the bottom half of the draw, although he hasn’t added to his resume of 14 majors since the taking the French Open in 2014. “Being in the quarterfinals of a Grand Slam after couple of years not being there is very special for me,” said Nadal, who last progressed this far at the 2015 French Open and hasn’t won an Australian title since 2009. Serena Williams kept her bid for an Open-era record 23rd major title on track with a 7-5, 6-4 win over 16th-seeded Barbora Strycova to reach the quarterfinals of the event for the 11th time. Mirjana Lucic-Baroni reached the semifinals at Wimbledon in 1999 as a 17-year-old and, after a long, difficult time off the tour, she has returned to the quarterfinals of a major for the first time since then.