Glasgow Tigers will have to produce their biggest performance of the season to overhaul Sheffield and make the SGB Championship playoffs final.
The Tigers were humbled by Sheffield at Owlerton on Thursday night in a rampant 59-31 victory for the hosts.
The clubs meet in the second leg at the Peugeot Ashfield Stadium on Tuesday night, when Stewart Dickson's side must rack up 60 points if they're to make it through to face either Edinburgh or Ipswich in the showdown for silverware.
On another tough night for Glasgow, only Richard Lawson and guest James Sarjeant shone, scoring double figures - with Richie Worrall, Aaron Summers and Dan Bewley all struggling to make their mark along with guest reserve Alfie Bowtell, who failed to score.
The damage was done early on as Sheffield raced into a 13-5 lead by heat three - and were 40-14 ahead after nine races.
Glasgow spared their blushes slightly by hauling back four points over the course of heats 10 and 11, with Sarjeant winning heat 12 and Lawson heat 15 to push them over the 30-point mark.
Afterwards, skipper Summers apologised for the result - but insisted: "The fight isn't over yet. Bring on Tuesday and we'll give it our best to turn it around."
In the other semi, Ipswich beat Edinburgh 50-40 to take a 10-point lead into the second leg at Armadale on Friday night.
Before Tuesday, Glasgow have a big day on Sunday when they host the Championship Riders' Individual featuring the cream of the crop from British speedway's second tier - tapes up 3pm.