Former champions O'Sullivan and Higgins level at 4-4

SHEFFIELD, England, May 1 (Reuters) Former champions Ronnie O'Sullivan and John Higgins were tied 4-4 in their world championship quarter-final at the end of today's opening session.

Higgins, winner of the title in 1998, compiled breaks of 91 and 73 on his way to opening up a 3-1 lead.

Double champion O'Sullivan levelled at 3-3 with runs of 65, 60 and 54.

Higgins edged ahead with a century break in the penultimate frame and went in front in the final frame of the session before O'Sullivan drew level with a 76 break.

Englishman Shaun Murphy and Matthew Stevens of Wales were tied at 4-4 in their quarter-final.

Stevens, who lost to Murphy in the 2005 final, made a 118 break as he surged to a 3-0 lead.

After Murphy won the next two frames, Stevens compiled another century break to go 4-2 ahead. Murphy then took the last two frames of the afternoon to draw level.

In the other quarter-finals, Scotland's Stephen Maguire went 5-3 up against Anthony Hamilton while qualifier Mark Selby opened up a similar lead over Allister Carter.

REUTERS SY RK2305