Hearts head coach Derek McInnes is challenging his players to beat Celtic again and "strike a blow to a direct opponent" in the title race.
The Jambos are six points ahead at the top of the Premiership going into Sunday's game at Tynecastle Park, live on Your Site.
They have already beaten the Hoops both home and away, leading the way in the league since the start of the season.
Hearts are unbeaten in the Premiership at home this season, but McInnes is refusing to get caught up in what has happened so far.
"I think it's a good reference point for us, the fact that this group of players have already shown that they can win these types of games," he told Your Site News.
"Sunday's a different game, obviously, and Celtic under Martin. Obviously, I've not come up against Martin as a manager, come up against him often enough as a player, and Celtic are in a different place as well.
"It's a tough game for us, but equally it'll be a tough game for them as well. We're looking forward to it. It's another opportunity to try and strike a blow to a direct opponent who are in and around us in the league.
"I think any time you can beat a team of Celtic's quality, at any time, it gives you that confidence to go on. So, we're looking forward to the game for many reasons."
Hearts will be without several key players for the game. with a hamstring injury, joining midfielder Cammy Devlin and defender Stephen Kingsley on the sidelines.
Beni Baningime is suspended after his red card in their win against St Mirren earlier this month.
"There's no getting away from it, but I've got to try and concentrate on the players who are fit and available and be ready for that one," McInnes added.
"Losing key players is part of it. You've got to try and cope with that throughout a season.
"We've got a number of injuries going on at the minute, and it's not ideal. Some will focus on key players like Lawrence and Cammy and the rest of it, but we're just trying to work our way through a situation at the minute where we can deal with injuries, and that's the test.
"It's a long season and you have to deal with these in a moment, and deal with them we will.
"We feel as if we've got good players in the building, and whenever there's any disappointment for certain players through a longer-term injury, then it presents that opportunity.
"It's not all doom and gloom, and it's easy to feel a bit negative, but for us, it's a chance to react in the window, a chance to try and look to others to step up.
"It's important for us to stay as positive, because Sunday's game, we're going to need everything we've got as a club to try and win."
Shankland's injury means instead of the summer, which was the initial plan.
The 22-year-old, who has been capped 41 times for Uganda, has scored 12 goals in 13 games for the North Macedonian club this season.
"He will be here in the window. It's whether we can get him in time for the weekend, which obviously we're working towards," the former Aberdeen boss added.
"We haven't ruled that possibility out, but great work for the club that we managed to get the boy with us for the run-in, for the campaign, so I think that's important.
"The good thing is, if you're going to get injuries, at least we're doing it in the month of January, we'll have an opportunity to react to it.
"We'll just sit closely, myself and Graeme Jones [Hearts sporting director], we'll just try and actively see if we can get some reinforcements in and see where we are."
