Littler was again seeking a record fifth nightly win of the season, but blew a 4-0 lead in a 6-5 loss to Van Gerwen in the quarter-finals.
Manchester United fan Littler came out to boos from the Liverpool crowd, though he appeared to have shrugged those off as he did last year when claiming victory here.
The 18-year-old looked emotional as he left the stage after missing two darts for a 5-1 lead, and two match darts at 5-3.
World and defending Premier League champion Littler still remains top of the eight-player table and on track to qualify for the end-of-season play-offs on 29 May.
There was also an early exit in Liverpool for local hero Stephen Bunting on his homecoming, beaten 6-1 by Rob Cross in the last eight.
Dutchman Van Gerwen could not maintain his momentum in the semi-finals, going down 6-4 to Humphries, while Price defeated Cross 6-2.
It was a happier night for Price, a week after he said his darts were “blowing everywhere” in breezy conditions in Rotterdam.
“Sometimes I do throw my toys out of the pram when things don’t go my way, but I had a reason last week,” he added. “We don’t deserve to play in those conditions.”
