|Pro12: Edinburgh v Glasgow|
|Date: Sunday, 27 December Venue: Murrayfield Stadium, Edinburgh Kick-off: 15:05 GMT|
|Coverage: Watch on BBC Alba; listen on BBC Radio Scotland; video and audio streamed on BBC Sport website|
Chris Paterson believes "a calm head under pressure" could be the key to success in Edinburgh and Glasgow Warriors' annual double-header.
The Pro12 sides meet on Sunday at Murrayfield and then again at Scotstoun on 2 January.
As well as league points, the teams will be battling to win the 1872 Cup over two legs.
"Dealing with pressure is really, really important," said former Edinburgh and Scotland back Paterson.
"Your opportunities could be very, very few and far between. Your opportunity could be in the opening five minutes of the opening game and you've got to take it.
"You may not get another opportunity because everybody will be so tense over the two games. That's the key thing - keeping a calm head under pressure.
"You need some of your players, obviously, to get wound up and be more aggressive than others but you need the decision makers to be really clear under pressure and strike when you have opportunity to because there won't be a huge amount of opportunities."
Paterson, now an MBE, does some coaching with the Warriors and had two spells at Edinburgh as he became Scotland's most-capped and highest scoring player.
"It's your typical derby in many ways," he said of meetings of Scotland's two professional sides. "It's fiercely competitive on the field and off the field. There's a great tradition that the supporters compete as well.
"On the field, it's real - it's hard rugby, it's meaningful rugby, it's league points at stake but there's an 1872 trophy at stake as well.
"There's a real edge to it. What we have now is two teams that are really strong, really competitive. We've got reigning [Pro12] champions in Glasgow and you've got an Edinburgh team that are vastly improving - final of the European [Challenge Cup] last year.
"All that goes out the window when you come head-to-head. It comes down to you against your opposite number in a derby match and it's hard.
"They will be close. You've got two teams playing towards the top of their games, over two legs, it's an aggregate score in the 1872 Cup. The team that wins the first leg has a huge advantage."