Callum Davidson challenges his squad to replace Ali McCann and Jason Kerr

Callum Davidson urged his St Johnstone squad to step up and plug the gaps left by the departure of Ali McCann and Jason Kerr.

Defender Kerr, who captained the Perth club to a domestic cup double last season, joined Wigan on August 31 the day before 21-year-old Northern Ireland international midfielder McCann signed for Preston.

Ahead of the home Premiership game against Rangers on Saturday, Davidson, who revealed new loan signing Cammy MacPherson will have a scan on a shoulder injury, said: “Ali and Jason were very important players for us but probably, strength and depth, we are a little bit stronger.

“It is now up to players, there are two places up for grabs in the team so people really need to step forward and try to take that place, that’s the thing I am going to use with them.

“They will have to perform to a level where Ali and Jason got to so it is up to them to go and do that.

“If I was a player not playing, it would be a great opportunity for me to say, ‘here I am, I want to play gaffer, I am desperate to play’, not by words, more by actions, what they do on the training pitch and the pitch. So players over the next couple of weeks will get an opportunity to try and get a place in the team.”

In addition to bringing in MacPherson, Davidson’s secured the loan signings of Brighton defender Lars Dendoncker and Ali Crawford from Bolton later in the transfer window

Finland Under-212 striker Eetu Vertainen “will be involved” against Rangers after officially signing his contract on September 1.

However, midfielder Murray Davidson is recovering from a shoulder injury and is 50-50 while Canada midfielder David Wotherspoon returns from international duty on Friday.

Callum Davidson said: “We obviously brought Cammy in, we were looking at him anyway with the likelihood Ali was going so I was delighted to get him.

“Unfortunately, he popped his shoulder on Monday night in a reserve game so I don’t know how long he will be out for. So a bit of a blow for us, but again there are other players who can take his place.

“He is getting a scan today. With the shoulder it is how bad the surrounding ligament damage is when he popped his shoulder.

“It went back in again so hopefully there is not too much damage which can limit the time he is out because with Craig Bryson being injured as well, he is a really important signing for me.

“Hopefully I can get him back as soon as I can.

“Murray is 50-50, he damaged ligaments in his shoulder in LASK so it never rains but it pours. We have to monitor him.

“David is available, he has a game tonight so he will fly back straight afterwards.”