Ronny Deila understands why Celtic's supporters were so frustrated after seeing their side shocked by Ross County in the Scottish League Cup.
Celtic took the lead in Sunday's semi-final at Hampden Park courtesy of a goal from Gary Mackay-Steven inside the first minute.
However, the first-half dismissal of defender Efe Ambrose changed the complexion of the contest, with Ross County eventually running out 3-1 winners against 10 men.
The loss ended Celtic's hopes of completing a domestic treble, while also increasing the pressure on manager Deila despite him being named Scottish Premiership Manager of the Month for January.
"The fans are disappointed and I really understand that," the Norwegian told Sky Sports.
"Of course we have big ambitions, we have hopes and when something lets you down you get angry. That's something I understand from the fans as well. If not they wouldn't care and that would be a worse thing.
"So I have no problem with that and of course the players feel that as well.
"But in football there are always tough times to go with the good times. There are always ups and downs and now I have to see the longer picture."
Celtic return to league action on Wednesday, as they travel to Pittodrie to take on second-placed Aberdeen, who are six points adrift.
They will be without Jozo Simunovic - the defender is expected to be out of action for up to six weeks with a knee injury.
"Jozo damaged his inside ligament in his knee and will be out for four to six weeks," confirmed Deila.
