United are preparing for the semi-final at the 10,001-capacity Sportpark Hohenberg, which is home of third tier German side Viktoria Koln.
The sweltering August heat means sessions are being held later afternoon rather than midday, with recovery the immediate focus as attention turns to the one-legged semi against Sevilla.
"It's like a European Championship or a World Cup - you don't get a second chance, there is no tomorrow," Solskjaer told MUTV.
"You just know that you have to leave everything on that pitch, which is for me fine.
"It's a different set-up than we're used to. We're used to home and away, but for me this is the best scenario that we can finish this tournament.
"All the teams have played many games anyway. but now it's who is the mentally strongest?
"Who looks at the opponent and he's tired, I feel tired but he's more tired than me.
"You've got to be strong mentally, concentrated, focused and any of these games can be decided, will be decided, on marginal decisions or finishing.
"So, we've just got to keep them focused and with the right attitude."