Callum Davidson says the defeat to Rangers was St Johnstone's best Premiership performance of the season so far.
But he believes basic errors when they were 1-0 up on the champions cost them priceless points.
Saints got their noses in front through Michael O'Halloran's goal in Perth.
But a rash tackle from Hayden Muller gifted Gers a penalty to level and after Ali Crawford missed a cracking chance for the home side – they were undone by James Tavernier's stunning winner.
Davidson couldn't fault his players for their effort who are still without a domestic victory this term.
But he's urged them to cut out the mistakes if they're going to challenge teams at the top end of the table.
After the 2-1 defeat, he said: “It was a fantastic finish from Michael but my biggest disappointment was the five minute spell after it.
“We made a lot of basic mistakes and allowed Rangers to apply pressure.
“We made a mistake for the penalty because you can't go to ground when there's loads of bodies in the box.
“That gave Ryan Kent a chance to – not hang a leg out – but contact was made. It gave Rangers an opportunity to come back into the game.
“After that, we settled down but again, little basic mistakes cost us.
“It's a wonder strike from Tavernier but I'd have liked more pressure on the ball at that point.
“It's funny because outside the European games, that's probably our best performance.
“It was really pleasing especially with all the changes we've had.
“But we need to put our finger on why we're making the errors and understand why. Do we switch off?
“Is it concentration levels? Or is it just experience because we have two 19-year-olds in defence.
“When you come up against a top team like Rangers you can't switch off. You have to do the basics well and if you don't, you're in trouble.
“It's frustrating not to take more chances. Ali hasn't played much football but he got himself in a good position for the chance.
“The effort was brilliant, I'm just disappointed for the players that we didn't get more from the game.
“I thought we worked unbelievably hard. We had to make numerous changes at the back but we actually performed really well defensively, especially in the first half.
“We limited Rangers to hardly any clear cut chances.
“I asked them to be a bit braver in the second half and when we were, we got chances from it.”
