Defending champion Luke Littler hit back from 9-6 down to beat Josh Rock 16-12 and reach the Grand Slam of Darts semifinals in Wolverhampton.

World champion Littler, who has yet to be beaten in the tournament, won seven legs on the spin to open up a 13-9 lead and saw the match out to set up a last-four clash with Danny Noppert.

Littler averaged 105.18 and landed 11 180s compared to Rock’s 101.46, while the Northern Ireland world No. 10 hit 12 180s.

Rock edged into a 3-2 lead after an 84-checkout — with both players averaging 110 — and after Littler produced a 78 finish, the match was locked at 5-5 after 10 legs.

Littler fell 7-6 behind and, after missing his double in the 14th leg, Rock won against the throw on his way to opening up a 9-6 advantage.

But Littler came storming back, winning the next seven legs to move 13-9 in front and although Rock stopped the rot to take the next two, he could not make further in-roads on his deficit.

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At 15-12 up, Littler could afford to miss three attempts at double 10 before sealing victory.

Dutchman Noppert beat German Lukas Wenig 16-8 in his quarterfinal, while world number one Luke Humphries will play another former world champion in Gerwyn Price in Sunday’s other semifinal.