Michael van Gerwen has struggled to qualify for the fifth round of the UK Open in Milton Keynes on Friday.
The defending champion narrowly beat Scott Mitchell (10-8) in the fourth round.
Dirk van Duijvenbode stunted after a thriller against Gary Anderson (10-9).
Van Gerwen played a very unstable match against Mitchell, the world champion at the BDO in 2015. He started rough, with a 0-2 and 2-3 deficit, but then had a strong phase and took a comfortable 6-3 -head Start.
With that, Van Gerwen seemed to have made an unbridgeable gap, but Mitchell surprisingly came back to 7-7 due to a slump and even a 7-6 and 8-7 lead.
However, Van Gerwen was back to class in time and took the following three legs.
Van Gerwen is on the hunt for his fourth title at the UK Open - he was the best in 2015, 2016 and last year - and his first this year.
He was immediately eliminated at The Masters and came no further than one semi-final place in the first four Players Championships.
Van Duijvenbode shows resilience against Anderson
Van Duijvenbode seemed to have to acknowledge his superiority in Anderson in a repeat of the quarterfinals at the last World Cup, when Anderson triumphed.
He was 5-2 behind, but with only 37 arrows he evened the score (5-5) and then he even took the lead 7-5.
Anderson, however, did not give in and tied the score (7-7).
Van Duijvenbode therefore had to force another break.
It looked like that was not going to happen, but in the decisive nineteenth leg he did so thanks to starting scores of 140 and 135.
Van Gerwen and Van Duijvenbode only had to enter the fourth round because of their place in the top 32 in the world rankings.
There will be a draw for the fifth round after the completion of the fourth round, as there is an open draw in each round from the fourth round onwards.
Noppert and Meulenkamp also in the fifth round
With Danny Noppert (10-6 against Glen Durrant) and Ron Meulenkamp (10-6 against Steve Lennon), there are still two Dutchmen in the fifth round for the time being.
Jeffrey de Zwaan (5-10 against Devon Petersen), Vincent van der Voort (6-10 against Max Hopp) and Jermaine Wattimena (6-10 against Callan Rydz) did not make it in the fourth round.
Raymond van Barneveld experienced a disappointing return to a television tournament earlier on Friday.
The five-time world champion, who captured a Tour card from the PDC last month, immediately lost his first match to Alan Soutar in the second round (3-6).
The UK Open, the 'FA Cup of darts', normally takes place in Minehead, but will be held behind closed doors in Milton Keynes this year due to the corona measures.
The fifth and sixth round are scheduled on Saturday and the quarter-finals, semi-finals and final on Sunday.