Miami, FL (SportsNetwork.com) - Defending champion Novak Djokovic and John Isner both won their respective matches on Thursday and will square off in the Miami Open semifinals.

The top-seeded Djokovic, a winner of this ATP Masters 1000 event four times, got through sixth-seeded David Ferrer 7-5, 7-5 for his eighth straight victory over the Spaniard.

Ferrer fought off a match point and earned a break to even the match at 5-5 in the second set, but Djokovic broke right back and held serve to close it out.

Djokovic is looking to become the first player to complete the Indian Wells-Miami sweep on three separate occasions.

His next challenger is the American favorite Isner, who ousted Japanese star Kei Nishikori. The 22nd-seeded Isner vanquished the fourth-seeded U.S. Open runner-up in 6-4, 6-3 fashion in 70 minutes at Crandon Park.

Isner won the final eight points of the first set, breaking Nishikori at love to close it out. He then ran out to a 3-0 lead in the second and was never threatened.

The 29-year-old Isner is a perfect 6-0 in his career Masters quarterfinals after smacking 13 aces past Nishikori. The towering North Carolina native broke his world No. 5 Japanese counterpart two times, while Nishikori failed to enjoy even one break-point chance on Day 9 of the 12-day tournament.

Coming into Miami, Isner had lost 11 straight matches against Top-10 opponents since his run to the 2013 Cincinnati final. He upended Djokovic in the quarters in that event for one of his two victories over the Serb superstar in eight career meetings.

The other semifinal was set on Wednesday, when third-seeded two-time Miami champ Andy Murray topped Austrian Dominic Thiem in three sets and eighth- seeded 2010 finalist Tomas Berdych blitzed Argentine Juan Monaco in straights. The 2015 Australian Open runner-up Murray captured this event in 2009 and 2013 and was the Miami runner-up in 2012.

This week's champ will earn $900,400.