Mark Allen has established a 5-3 lead over Mark Selby after the first session of their World Championship semi-final.

Selby, a four-time champion, has grown into the tournament and appeared at his efficient best as he took the opener with a 123 break.

Breaks of 63 and 66 did not prevent Allen falling 3-2 behind, but the Northern Irishman was able to reel off the final three frames to seize the early initiative.

Although he was devoid of a century, Allen made further breaks of 64, 60 and 78 respectively to prevent Selby from gaining a stranglehold of the contest.

Earlier in the day, Si Jiahui produced some ruthless snooker to open up a 5-3 advantage over Luca Brecel, who won seven straight frames to beat Ronnie O'Sullivan on Thursday.

In sharp contrast, the Belgian watched debutant Si reel off four successive frames to move 4-1 ahead, making breaks of 125, 102 and 97 in the process.

The Chinese youngster would have moved 5-1 in front had he not missed a simple black when 53-1 ahead in the sixth, Brecel responding with a 72 clearance.

While Brecel took the seventh to capitalise on his let-off, Si responded in the final frame of the session, taking it on the black to open up a narrow advantage. body check tags ::