The 22-year-old Finnish striker is finally available for selection after a protracted bureaucratic process which delayed the approval of his work permit and time spent in quarantine following his arrival from Ilves Tampere.
Davidson is hugely enthused by the ability and potential of Vertainen who scored in a closed-door friendly against Brechin City on Monday night and is now firmly in contention to make his competitive debut against the Premiership champions.
“Eetu has had a bit of a close season after being in isolation and training by himself,” said Davidson. “He only trained once with us before the game with Brechin on Monday.
“But you can see he is a big, strong lad with great feet and an eye for a goal. I’m pretty excited about him and hopefully we can get him on the pitch as soon as we can.
“He has been working hard on his own and he played games in Finland before coming here so we will probably accelerate him.
“With all the injuries we have currently got, it’s one area of the team where we are still quite strong just now. I can probably pick from all my attacking players.”
Davidson’s other three recent recruits were also involved in the Brechin bounce game, although midfielder Cammy MacPherson suffered a shoulder injury. Defender Lars Dendoncker, signed on loan from Brighton, and former Hamilton midfielder Ali Crawford, on loan from Bolton, could feature against Rangers.
“With Cammy and Ali, they already know how the club is run,” said Davidson. “Lars and Eeetu might take a little longer to realise what we are all about and what Scottish football is all about.
“It can be frenetic, played at a real high tempo, and they have to adapt to that. They have ability, that's why they are here, and we have to make sure we get that onto the pitch as quickly as we can.”
St Johnstone famously knocked Rangers out of the Scottish Cup at Ibrox in the quarter-final stage last season and also held Steven Gerrard’s side to a 1-1 draw in their most recent league meeting at McDiarmid Park.
“For me, it was about the intensity we played at in those games,” added Davidson. “You can’t afford to come off it.
“We have shown in Europe this season we can play with intensity and energy at that level. With the good teams, if you come off that they will just pop the ball around you and create chance after chance.
“That’s how I like to play, with a high intensity game at the right times. If the players don’t do it, they won't play in my team. It’s as simple as that.
“Rangers are the benchmark. They were fantastic last season. They have tweaked it a bit but they haven’t made many changes.
“They are probably ready to start kicking into form so we have to make sure we do the right things against them to make it difficult and try to frustrate them.
“We will have a few changes for Saturday but it will be more experience gained for my players and they have to make sure they take something from it.”