ADELAIDE - Former U.S. Open champion Marin Cilic recovered from a mid-match wobble to beat American Tommy Paul and reach the semi-finals of the Adelaide International 2 event on Thursday, but Russian Karen Khachanov was knocked out by Frenchman Arthur Rinderknech.
Fourth seed Cilic dug deep to seal a 6-4 2-6 6-3 win over the in-form Paul, who had won 12 of his past 14 matches coming into Thursday's contest.
Third seed Khachanov, who was runner-up at the Adelaide International 1 event, suffered a 7-6(7) 7-5 defeat by world number 58 Rinderknech.
Elsewhere, French qualifier Corentin Moutet secured a 6-4 6-4 win over Brazil's Thiago Monteiro, setting up a clash with Rinderknech in the last four.
Croatian Cilic said he was pleased with his performance so far this season, having also reached the semi-finals of the first event in Adelaide last week.
"Fantastic start to the year, tough matches," Cilic said in his on-court interview. "He (Paul) played really well throughout the match and just a couple of points, in the end, decided the difference in the third set."
Cilic will next face Thanasi Kokkinakis, who fought back from a set down to overcome Aleksandar Vukic 6-7(5) 6-3 6-2 in an all-Australian clash, after turning to eye drops at one point during the first-set tiebreak to ease problems with his vision.
"There's no way I should be losing this match, that's what I was thinking to myself the whole time," Kokkinakis told a post-match news conference.
"He came up with some good serves, his credit, on some. He didn't come up with a good serve 13 times in a row. A lot of that was on me."
In the women's event, third seed Coco Gauff reached the last four with a 6-3 6-4 victory over Croatia's Ana Konjuh but American Madison Brengle was forced to retire from her match against Alison Riske due to a slight calf injury.
Gauff said she had improved since losing to world number one Ash Barty last week and hoped to build on her performance heading into next week's Australian Open Grand Slam.
"I took a lot of positives from that match and I think I've been improving and working on it this week," the 17-year-old told reporters.
"I'm hoping to continue that momentum through the rest of this tournament and through all the Australian Open."
Gauff will take on compatriot Madison Keys after the 2015 Australian Open semi-finalist battled past eighth seed Ludmilla Samsonova 6-3 3-6 6-3.
Earlier, Brengle retired from the match with the score 3-3 in the first set, sending Riske through to the semi-finals where she will meet fourth seed Tamara Zidansek.
The Slovenian booked a spot in the semi-finals by beating American Lauren Davis 7-6(4) 7-6(7) in a match that lasted over two hours. (Reporting by Manasi Pathak in Bengaluru and Anita Kobylinska in Gdansk; Editing by Richard Pullin and Christopher Cushing)