STUART Armstrong today told his Celtic team mates they'll need to keep cool heads in the white-hot atmosphere of the Scottish Cup semi-final against Rangers if they want to win.

Ronny Deila’s side has been defeated in the last two semi-finals they have played at Hampden against Inverness Caledonian Thistle and Ross County – after having players sent off in both games.

The Parkhead club was leading the Scottish Cup semi-final against Caledonian Thistle 1-0 last year after an early goal by Virgil van Dijk and appeared to be heading for a comfortable victory.

However, goalkeeper Craig Gordon was red carded for bringing down Marley Watkins in the second half and his team mates ended up losing the match 3-2 after extra-time.

That painful and hugely controversial defeat scuppered the Scottish champions’ hopes of completing the fourth domestic treble in their history.

More heartache was to come for Celtic at the National Stadium in the League Cup semi-final this January when they crashed to a shock 3-1 loss to Premiership rivals County.

They took the lead through Gary Mackay-Steven in the very first minute, but had centre half Efe Ambrose sent off in the first half and finished up on the receiving end of a 3-1 reverse.

There has been huge hype surrounding this match - which is only the second Old Firm games in four years - and a crowd of around 50,000 are sure to create an intimidating environment for the players to do battle on Sunday.

Armstrong, the former Dundee United midfielder who is hoping to get the nod to play in his first Glasgow derby game this weekend, knows it will be vital not to fall foul of referee Craig Thomson.

“I wasn’t involved in the Inverness game (Armstrong was cup tied), but the Ross County game was obviously disappointing,” he said. “But circumstances were difficult in that game with the sending off. We had a great start and it petered out. We just need to focus in this one.

"I can imagine that maybe it hots up a little bit with people’s tempers. You need to keep calm and keep discipline and don’t get carried away. We must focus on us. Our aim is to get to the final of the Scottish Cup.

“Everyone wants to play. You can see in everyone’s face that they want to be involved and play their part. Not only playing a big semi-final against Rangers, but also help the team get into a final and being part of that success.

“There is a lot of competition for places and a lot of boys playing well. I’m under no illusions of how big it is. I’m sure that scoring a goal and winning a game means a lot to everyone, the fans and everyone involved at the club.

“I’m sure the coaches at the club who have been involved in the game will offer a few words of advice on how to handle the environment we will be playing in. But I think everybody at the club knows that it’s a huge game that we want to win.”