World number one Michael van Gerwen has admitted that he must improve his performance if he is to keep on progressing at the Grand Slam of Darts.
The Dutchman produced a below-par showing in last night's 10-4 victory over Terry Jenkins, which secured his place in the quarter-finals of the competition.
Despite having already seen off Darren Webster, Kim Huybrechts and Jan Dekker, Van Gerwen believes that he can still move up a few more gears.
"I'm not playing well. I'm not really playing well in the whole tournament," he told Sky Sports News. "I need to look in the mirror and work out what's gone wrong. I can do a lot better, my finishing at the end was good but I'm not happy with my performance.
"But sometimes it doesn't matter how you win – a win is a win. But I always want to play well, just sometimes it's very difficult to do that. It takes a lot of energy."
Van Gerwen will take on Huybrechts once more in the quarters.