Saturday's 2-2 draw with Brechin at Recreation Park saw the Wasps fall six point behind their promotion rivals at the top of the table but for Alloa's number nine, the players have the confidence and ability to catch them.
Grehan told Advertiser Sport, "It would have been better if we had got the win today but we won't get ourselves down. Obviously we are trying to keep in touch with Queen of the South so we are all disappointed to have conceded ground today from a winning position and at the end of the day we see it as points dropped but it's still a point at the end of the day. We wouldn't be playing football if we didn't think we could catch them!"
Grehan was almost substituted before his wonder goal that put the Wasps into a 2-0 lead and he admits that he was disappointed that his goal didn't save him from the hook. Worse was to come for the former Motherwell trainee as he watched his side relinquish their lead from the bench but he believes that most of their demise was due to their opponent's good play.
Grehan said, "I saw Thommo ready at the sidelines as we broke forward so I knew it was probably going to be me coming off but then when I scored I thought it would give me more time to improve my display but it wasn't to be. I was just delighted to have scored as it put us in a good position at that point.
"The game is never done and dusted in football. Brechin to their credit came back into it and while it was poor goals for us to concede, fair play to them for keeping going. It was definitely disappointing to concede the lead because we have been playing well, we had won the four on the bounce and it looked like it was going to be five but it just wasn't meant to be."
Grehan was delighted to repay his manager's faith in him with another goal and know's the team will have to be at the top of their game now as they travel to Ochilview for a difficult test this weekend.
He said, "We now travel to face Stenhousemuir which we know will be a hard game and we will have to pick ourselves up during the week and get focused for that one. I don't like to set targets but that's me on eight for the season now and I'm a striker so I'm delighted to score.
"The gaffer has kept me in the starting line up and even although I didn't have my best game against Brechin, at the end of the day it is goals that you get judged on and it was nice to put that one away. I always feel like I can get a goal while I'm on the park and because of the quality players we have here when I get chances I'm always confident I can put them away."
Meanwhile, last week was a busy week of the club as they let Ryan Miller, Blair Munn and Nicky Locke all join Sauchie Juniors on loan until the end of the season while Callum Tapping joined the club on loan from Hearts.
The young midfielder's arrival is a welcome one according to his new team mate.
Grehan added, "Callum has joined now and it's great to see the manager continue to add quality. He only joined us last week but when he came on towards the end he looked comfortable on the ball. We always welcome that kind of player, his style will suit us well."