LONDON (Reuters) - Marin Cilic's miserable record at the ATP Finals continued as he was beaten 7-6(5) 7-6(1) by Germany's Alexander Zverev on Monday -- his ninth defeat in 10 round-robin matches at the O2 Arena.
Almost a year to the day since Zverev marked his debut in the season-ending showpiece by toppling the big-serving Croat, the 21-year-old again prevailed in a sometimes scrappy contest to take his career record over Cilic to 6-1.
Last year he failed to back up his victory over Cilic, losing his next two group matches to Roger Federer and Jack Sock to miss out on the semi-finals.
With a year's more experience and on the back of a season in which he leads the ATP Tour match wins list with 55, Zverev has put himself in a strong position to claim one of the top two places in the Gustavo Kuerten group.
World number one and tournament favourite Novak Djokovic faces American debutant John Isner later on Monday.
Cilic, ranked two places below world number five Zverev, will be scratching his head at how he allowed an opening set in which he dominated to slip through his fingers.
The 30-year-old had point for a 4-0 lead and another one for 5-1 but allowed Zverev to claw his way back from a 1-4 deficit to take the set on a tiebreak, sealing it with a backhand pass after dragging Cilic to the net with a dropshot.
Breaks of serve were exchanged in the second set before Cilic was required to save a match point at 4-5.
Cilic survived more Zverev pressure at 5-6, winning a long baseline exchange at 30-30 to set up another tiebreak.
Just as in the day's first shootout it was Zverev who jumped into a lead against an edgy Cilic who double-faulted at 1-4.
Zverev nailed a trademark backhand winner down the line to earn five more match points and converted the first with a powerful first serve that Cilic could only fend into net.
"I was just trying to get myself going, trying to get the energy up. It worked out," Zverev, who vented his anger in the direction of coach Ivan Lendl in the early stages, said.
Australian Open runner-up Cilic now faces the prospect of a fourth group stage exit at the tournament and says failing to capitalise on leads is becoming an annoying habit.
Last year he was a break up in the deciding set against Zverev, then a set to the good against Roger Federer and Jack Sock but lost all three matches.
"It's not the best thing that I'm doing, creating opportunities and having most of the time leads in the match and then I drop them," he said.
"Hopefully, I can build up on this match today and that I can play better."
(Reporting by Martyn Herman; editing by Pritha Sarkar)
