The Rossoneri were beaten by a late Diego Costa goal, but the Dutchman believes his team will improve before March 11 and has faith they can turn the tie around
The Rossoneri were dominant for large periods of the game but were made to pay for their profligacy when Diego Costa headed home an 83rd-minute winner in the first leg of the last 16 tie at San Siro.
Seedorf was pleased with the way they performed against La Liga opposition but not could help but rue his team's inability to score.
"I'm happy for what I've seen from the team: the first half was very good, but we missed the vital goal," the Dutchman told Mediaset Premium. "In the second half after the first 20 minutes we lost our legs a bit and eventually conceded to a great team like Atletico.
"I think it was a good game, but we conceded from a set-piece situation which can always happen. But this is only the first leg and there is a second to play in Spain.
"We are trying to recover on all fronts and to better manage the physical declines that occur in the game. However, I have seen an improvement from my players this evening."
Seedorf's men now must win at the Vicente Calderon, a daunting task for a side which have struggled away from home this season, but the Dutchman has faith in his team and thinks Milan will improve before the March 11 clash.
"There is still plenty of time before the return leg and I hope that the team can make some important steps forward in that time," he added. "We have confidence after this game, but a lot of things can still change in the coming weeks.
"Football is not basketball and there is no shame in losing 1-0. We had players who have not played together tonight and it is difficult to immediately find that fluency.
"I believe that over time the players will know better and will be able to grow and build more chances to score and with greater frequency."