St Johnstone manager Steve Lomas has urged his players to forget the implications of Hearts' defeat last night and focus on atoning for their Fir Park thrashing when they face Celtic.
An under-strength Saints suffered their second defeat since the Clydesdale Bank Premier League split when they went down 5-1 to Motherwell on Saturday.
The heavy loss left the Perth side just a point ahead of Hearts in the race for fifth place and a guaranteed Europa League berth, but Motherwell did them a favour last night by winning at Tynecastle.
Even if St Johnstone lose against the champions, they know victory against Hearts in Edinburgh on Sunday would be enough to clinch a European spot, but Lomas is more concerned with making sure his players improve on what he described as their worst performance of his reign.
He said: “We can only look after ourselves. We let ourselves down as a group on Saturday.
"We want to bounce back and put in a performance against Celtic no matter what team they put out.
"That's what we will be looking for first and foremost - a reaction from Saturday.
"When you go to the Old Firm you have got to put in a performance. "You certainly don't go there and play badly and get a result.
"Our boys are an honest set. They will be hurting from Saturday and wanting to make amends."
Saints have already played at Celtic Park twice this season, winning 1-0 under Derek McInnes in September before seeing several crucial referee decisions go against them in a 2-0 loss in March.
But they might not be able to call upon the same resources this time with a number of players fighting fitness problems. Chris Millar, Cillian Sheridan, Dave Mackay and Callum Davidson are all touch and go while the suspended Francisco Sandaza and torn-hamstring victim Lee Croft are definitely out.
Lomas said: "We have quite a few issues so we will have to wait to the last minute to name our team. We are a little bit in the dark.
"The last few weeks have been very difficult with suspensions, injuries, sendings-off and people pulling out in warm-ups and with late injuries.
"Three games in a week hasn't helped, it has all happened in our busiest period."