Motherwell enhanced their chances of continental competition with a 2-1 win over Inverness, a result that moved them up into second place in the Scottish Premiership.
Henri Anier's 39th-minute goal gave Motherwell the lead but Inverness levelled in the 74th minute as youngster Ryan Christie scored his first goal for the club.
Any hope Caley had of giving their own European ambitions a boost were ended eight minutes from time as Iain Vigurs struck the winner for Motherwell.
McCall said: "Stuart Carswell is due an operation, as is Paul Lawson, while Keith
Lasley has a suspension coming up soon.
"Craig Reid could have a broken toe, while Henri Anier has taken a knock to his ankle. However, we were able to rest Lionel Ainsworth tonight ahead of St Mirren on Saturday.
"We've now got six games to go. The players can get all the rest they want in the summer unless we're back on July 3 for the qualifying rounds of the Europa League.
"It's not a time now to rest. The players have got to give everything and they did that tonight."
Inverness manager John Hughes conceded that his side might just be too far behind now in the race for a European spot with them sitting 10 points behind
He said: "The other teams are getting away from us now. However, we have to regroup and go again.
"This is a test of character for us. We can't sit back and rest on our laurels."