Tomas Berdych believes that his previous experience of having played at the season-ending ATP World Tour Finals helped him to defeat Marin Cilic this afternoon.
Heading into the contest at London's O2 Arena, both players knew that a defeat would see them eliminated from the tournament at the group stage.
Czech Republic number one Berdych has featured at the event five times, while US Open champion Cilic was making his debut - something that the 6-3 6-1 victor has claimed was the difference.
"It's not my first year and losing the first match is something that I've experienced in the past. I know how to do it and I think my experience was the biggest difference today," he told Sky Sports News.
On Friday, Berdych will face world number one Novak Djokovic, whom he may need to beat to reach the semi-finals.