The play-off positions in the BetwayPremier League of Darts are beginning to become clearer after night 13 in Birmingham. With just two weeks of fixtures left to play, two players have already been confirmed in the crucial top-four places. St Helens' Dave Chisnall joined the top seed Michael van Gerwen as a guaranteed qualifier last night. PDC World Champion Gary Anderson slipped back into fourth position after an inspired Raymond van Barneveld claimed a double success. It was an unlucky night for Adrian Lewis though, as his qualifying hopes nose-dived with two defeats.

Chisnall and Lewis were first on stage at the Barclaycard Arena.

With Lewis doubling up at the Midlands' venue, he had a big opportunity to stake his claim on the play-off positions. Sadly for him, things did not quite go to plan. Despite a promising opening against Chisnall, as he took an early 3-1 lead, Lewis ultimately slumped to a 7-4 reversal. The Stoke player slightly outscored Chisnall on the night, but his lower checkout conversion percentage (29% against 47%) proved to be the difference. Chisnall's victory confirmed his place in the play-offs, although both van Barneveld and Anderson can still overtake him for second place.

Van Barneveld also doubled up on the night but enjoyed a far more positive result from his first game against Anderson. Neither player was at their best, missing several doubles during a tense tussle. The Dutchman seemed off the pace as he fell 4-0 behind to the Scot but then found some of the forms he has enjoyed in recent weeks to storm back.

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Five legs in a row gave him a narrow lead, but they were level again in leg ten as Anderson found a 13-dart finish. 'Barney' edged out to 6-5 in the next leg and closed out the game 7-5 as Anderson missed doubles in the decider. The game included an unsavoury incident, as Anderson claimed that his opponent had stamped when passing him in mid-throw. The Dutchman did not concur, but it still rankled with the Scot at the end of the match.

The highly-anticipated clash between league leader van Gerwen and Phil Taylor delivered the best scoring averages of the evening. 'Mighty Mike' took the match 7-4 to re-affirm his favourite's tag for the overall crown. With a 112.91 average in his favour, Taylor did admirably well to stay in touch. His own three-dart score consistency of 107.58 would have won any of the other matches in Birmingham. The defeat sees the 16-time World Champion back in 5th place, three points off the top four. It now looks to be a tall order for him to stay in the competition.

Lewis' second match against van Barneveld proved a thoroughly disappointing affair for him and his chances in the league. Averaging under 90, he could do little as the Dutch maestro claimed a 7-2 victory. Even two 132 checkouts proved to be no consolation for Lewis. Van Barneveld broke his throw three times and took out a wonderful 161 finish of his own.

James Wade and Stephen Bunting shared a point apiece in a low-key 6-6 draw. The result was of little use to either player, as their qualifying hopes are now over.

The action moves on to Newcastle next week, with Taylor desperately needing a success against Anderson, a repeat of this year's world final.