Underdogs David Gilbert and Gary Wilson rose to the occasion to give their established opponents plenty to think about on the opening day of the World Championship semi-finals at the Crucible.

Gilbert came close to a maximum break as he marked his debut in the venue's one-table set-up in style by forging a 5-3 overnight lead against four-time champion John Higgins.

And qualifier Wilson also gave title favourite Judd Trump all he could handle with a magnificent 140 total clearance capping an excellent evening session from which the pair finished level at 4-4.

Higgins and Trump had started as the overwhelming favourites to set up a repeat of their 2011 final showdown against opponents who have spent the best part of a decade battling for their tour survival.

In the same year Higgins beat Trump for the title, Gilbert was having to re-qualify for the tour through Q-School, while Wilson was scrapping for a second chance playing low-key club matches in his native north-east.

Gilbert showed early nerves as he slipped two frames behind but staged a sparkling recovery including potting 15 reds and 14 blacks to raise hopes of clinching the £50,000 maximum jackpot.

No stranger to 147s after potting the 147th during a Championship League match in January, Gilbert was forced to cross-double the final red and ran out of position on the black.

But it proved a strong response from Gilbert after he had missed a golden opportunity to win the previous frame when he got the snooker he required only to miss the green off its spot.

Gilbert had already shown his mettle by pulling level with a break of 94 in the fourth frame, and he would finish strongly to take the final three frames of the session.

Wilson's Crucible odyssey shows no signs of ending after a remarkable tournament which saw a final-frame win over Luca Brecel followed by strong wins over Mark Selby and Ali Carter.

Neither the fabled one-table set-up nor Trump's reputation seemed set to faze him, and after sharing the opening two frames Wilson compiled his superb clearance which was only one short of Trump's current tournament best.

Trump hauled himself level by the mid-session interval despite a series of costly mistakes, and a high-octane 39 in the next was evidence of his mounting frustration.

Wilson won two scrappy frames in a row to go back ahead before Trump seized another second chance to make a break of 54 and ensure the pair will be level going into the next sessions on Friday.