Football: Powers of recovery critical for battered Old Firm.
CELTIC and Rangers are both licking their wounds as they enter the Old Firm arena today.
The level of damage inflicted in Europe last week could decide the outcome.
Gordon Strachan's players have plenty to be proud of after staying on level terms with the magicians of Milan over three hours of action in the Champions League.
But they were physically exhausted on Wednesday night as their brave bid for a place in the quarter finals went to an extra half hour before the brilliant Kaka finally shattered their dream.
The damage to Rangers is more psychological after their impressive run of form ended on Thursday night with a dire display against Osasuna in the UEFA Cup.
You could argue that after playing their get-out-of-jail card against the Spaniards - Brahim Hemdani's perfectly-struck stoppage-time equaliser at Ibrox - Gers might feel lucky at Celtic Park today.
But a wily manager like Walter Smith will look beyond the great escape, that keeps alive their hopes of prolonging the European adventure, and examine what went wrong with his misfiring team.
It was the sort of disjointed display that might not have surprised us had Paul Le Guen still been at the helm.
But since Walter returned for his second spell at Ibrox we'd seen nothing like the disarray on the pitch that dragged the Frenchman's regime on to the rocks.
Rangers hammered Hapoel Tel-Aviv 4-0 at Ibrox to reach the last 16 of the UEFA Cup and have picked up 16 SPL points in six league games with Smith in charge.
There was no reason to scream from the rooftops that Rangers were back where they should be - but there were clear signs of progress.
There was a solid shape to the team and a safe and secure feeling that had been noticeably missing.
Now I'm not saying that the miraculous 1-1 draw with Osasuna - the performance rather than the result - takes Walter, Ally McCoist and Kenny McDowall back to the drawing board.
But it was a serious step back for Rangers after several sizeable paces forward in the last couple of months.
Defensively, why did Rangers sit in so deep and invite the Spanish side to forage forward?
Why was the quality of passing and possession so poor? Could nothing have been done to get solo striker Kris Boyd out of his isolation?
There were more questions than answers about Rangers' showing.
Some contributions - from the likes of Ugo Ehiogu, Kevin Thomson and Chris Burke, to name but three - were seriously sub standard.
We'll find out this afternoon how much damage has been done to Rangers' confidence as they prepare for their toughest test since their change of manager. We'll also be able to evaluate the knock-on effect for Celtic of two hours of high-intensity European football at the San Siro and the emotional drain of their ultimate defeat.
I'm sure they will get over the disappointment of losing out to Milan after running them so close for so long - it should be easily forgotten given the importance of the match against their old rivals.
What can't be counteracted quite so easily is the sheer physical effort expended by a group of players prepared for an energy-sapping 90 minutes who then had to drag their battered bodies through a further half-hour's play.
The adrenalin will be pumping again for Celtic come today's lunchtime kick-off - but when that wears off they may have to dig into new reserves of stamina.
Some of them are carrying injuries as well.
If central defender Stephen McManus (below) could have been rested in midweek I'm sure he would have been.
No way was he clear of his groin injury but he showed true grit and played superbly.
Striker Jan Vennegoor of Hesselink was another who took dedication to duty to an impressive extreme.
Hamstring trouble has dogged him in recent weeks but he ignored his aching limbs to produce more evidence of pounds 3.4 million well spent.
I thought the Hoops' two 20-year-olds - Darren O'Dea and Aiden McGeady - made their mark at the top level with performances of great maturity.
O'Dea outplayed McManus and Lee Naylor at the back, which is saying something.
Meanwhile, McGeady showed a combination of pace and close control that meant he looked far from out of place in such illustrious company.
And I take issue with the newspaper point scorers who marked Dutch teenager Evander Sno at no more than four or five out of 10. He might have been marked down because of his part in the breakaway that led to the only goal of the tie.
Yes, he was guilty of giving away the ball - but Celtic had three quarters of the pitch to stop the Milan attack.
And for a 19-year-old playing in one of football's most famous arenas, I reckon Sno played an important role. He'll be tired though, like the rest of the Celts.
So take your pick in this battle of damaged goods.