Another potential problem for Barcelona is their physical condition, after being subjected to a tough game against energy-sapping Atletico on Saturday while United enjoyed a free weekend to put their feet up - except manager Ole Gunnar Solskjaer, who travelled to the Camp Nou to watch the game against Atletico from the VIP seats (along with, strangely, Indian cricket legend Rahul Dravid).
To run on what was mostly soft sand every day was pretty energy-sapping.
Then it's on to the pavé, a hellish surface that ought to provide no end of entertainment on Tuesday, as the peloton clatters across seven sectors of these attritional, energy-sapping cobbles en route from Seraing to Cambrai.
Running through a bog is soul-crushing, demoralising and energy-sapping work.
To be honest, it is just a waste of energy, it is energy-sapping".
They have games in hand over the rest of the leading pack, but the fixture backlog means Danny Wilson's side play an energy-sapping programme of Monday-Saturday-Tuesday-Saturday-Tuesday-Saturday-Tuesday-Saturday for the remainder of the season.
We found that, similar to running the first few miles of a long race, responding to one or two help requests was not particularly energy-sapping on a given day for helpers.
The illness that has forced has forced the tenor Gary Lehman to withdraw from the title role in the Metropolitan Opera's production of "Siegfried," the third installment in the company's new "Ring" cycle, is an energy-sapping virus, his manager said on Thursday.
He now faces six energy-sapping, costly and gruelling contests in February before Super Tuesday on 6 March, when 10 states will be in play, including one of the biggest, Ohio.
Martinez said injuries played a part in Wigan's demise, especially as they had just 75 hours to recover from an energy-sapping game against City at a rain-soaked Wembley on Saturday.
