Derek McInnes hailed his 'tired' Aberdeen side after they survived a late St Johnstone onslaught to earn three crucial Premiership points.
"We had a lot of tired bodies out there after putting so much into that on Wednesday night," McInnes said.
"Sheer desire to get the job done got us there."
Aberdeen looked to be heading for a comfortable victory after two goals from Adam Rooney and strikes from Peter Pawlett and Niall McGinn put them 4-1 up with less than 20 minutes remaining.
However, goals from Steven Anderson and Tam Scobbie gave the Saints hope late on, but the Dons held on for the win.
"My biggest fear or concern for this game was the closing stages because of the lack of energy," McInnes told BBC Scotland.
"We put so much into the (Celtic) game. We picked a team with that in mind, that we thought would get us to a certain stage of the game and then making the changes to make us more solid.
"Obviously there are a lot of boys who played both 90 minutes in a short period of time. Games against Celtic do take it out of you. St Johnstone to their credit never know they are beaten."
Aberdeen have not tasted defeat in the league since October, and McInnes is thrilled with his side's performances in recent times.
"We're on a strong run. We haven't lost a game in over three months in the league. We've overcome some real challenges within that and today was another one.
"We're delighted with what the players are giving us at the minute. They are absolutely knocking their pan in.
"They give us spells of real quality but throughout it all there is 100% sheer commitment. At the minute it's going well, we just want that to continue."
St Johnstone manager Tommy Wright says sloppy defending was his side's undoing.
"Overall we probably did enough to get something out the game but you can't give the four goals away that we did," Wright said.
"Every one of them we've totally contributed to. We've only ourselves to blame because we've cost ourselves points today.
"Credit to the players for keeping going, but we really shouldn't be putting ourselves in that position."