- Tag results for Marin Cilic
Nishikori battled past second seed Cilic in Monte Carlo to reach his first Masters semi-final since July 2016.
Cilic and del Potro are the biggest names left in a field lacking star power thanks to the early exits of Federer and Novak Djokovic and the injury absences of Rafael Nadal and Andy Murray.
Juan Martin Del Potro continued his dominance over David Ferrer to book a spot in the Indian Wells fourth round.
Marin Cilic beat Argentine qualifier Carlos Berlocq 6-3, 6-2 to advance to the second round at the Rio Open.
Roger Federer became the oldest ever World No. 1 in the men's Association of Tennis Professionals world singles rankings.
Federer closed to within 155 points of Nadal after his win last month at the Australian Open against world Cilic.
Rafael Nadal remained in the number one spot in the men's Association of Tennis Professionals world singles rankings.
The tournament referee made a late call to close the roof and Cilic said it was tough to acclimatize to playing indoors after practicing outdoors earlier.
The Swiss tennis star beat world number three Croatian Marin Cilic in a hard-fought match 6-2, 6-7, 6-3, 3-6, 6-1 at the Rod Laver Arena on Sunday.
The 36-year-old Swiss marvel continues to defy the years and attrition rate to reach his 30th Grand Slam decider and a shot at his sixth Australian crown.
The world number six is the first Croatian man or woman to appear in the final at Melbourne Park as he guns for his second major title.
The Swiss ace is a clear favourite but the unseeded 21-year-old has already sent Novak Djokovic packing, proving anything can happen.
Marin Cilic has advanced to his first Australian Open final, beating Kyle Edmund of Britain 6-2, 7-6 (4), 6-2.
Sixth seed Cilic made the semis eight years ago but fell to Andy Murray, with another British player again standing in his way in unseeded Edmund.
Spaniard Nadal was trailing the final set 2-0 when he decided to give up to the leg injury.