The 23-year-old suffered a knee injury ahead of the campaign and another forward, Curtis Main, remains out with a persistent thigh problem.

Loan striker Ryan Edmondson has also had his injury problems and is yet to start a game, although he is fit now, which has meant another temporary signing, former Inverness winger Marley Watkins, has been left to lead the line.

Cosgrove offers a different type of option to Watkins and McInnes is delighted with the growing strength of his squad.

He said: "When the games have been open we have enjoyed it, we have a lot of speed in the team, whether it's (Connor) McLennan, (Jonny) Hayes, Watkins, (Ryan) Hedges, (Scott) Wright, those attacking options, when they have been at their best we have a lot of space afforded to us.

"When teams defend their box like United did on Saturday for a lot of the game, we could have done with somebody there with a bit of presence, a penalty-box striker, an experienced striker like big Sam, someone that makes them think twice about defending that deep.

"We got into so many good positions, I think we had 36 crosses, 18 shots, umpteen set-plays. So it's not just down to having a main striker there, a traditional number nine. We need everybody to contribute.

"But it's clear that someone like big Sam, who has been our top goalscorer and talisman for the last couple of seasons, I think would have posed teams like United on Saturday, and other games this season, a few more problems from defending so deeply."

As well as Cosgrove, recent signing Greg Leigh, Scotland defender Michael Devlin and winger Matty Kennedy are in contention following injury.

"None of the four of them will start but having the four back in and around things is very pleasing," McInnes said.

"The strength of the squad on Sunday.... a training session straight after a match day can sometimes be a tough one for those players to get up for, but when I saw the strength of it in terms of numbers and also the quality that we had, from the substitutes and these boys, it was such a strong training session.

"I am clearly going to have some headaches in terms of team selection in the next few weeks but I am really encouraged by the options and the level of player that we have got coming back in the squad."

Watkins is looking forward to getting more help up front with Cosgrove's return.

"His goalscoring record speaks for itself," the player on loan from Bristol City said.

"He is more of a target man and I'm more running channels or trying to get on the ball so I think we can do really well together.

"Some games you have just got to be patient and occupy the centre-halves and not be too much involved in the game which is frustrating but whatever is best for the team. Sam is a unit so he will be good to play with.

"In the past when I've played up top it's always been with another striker, but I have done all right up there. It's just good to have options obviously."