Derby County boss John Eustace spoke to BBC Radio Derby after Saturday's 2-1 defeat at Southampton.
"I thought first half we were excellent and in the second half we just ran out of legs. The second goal we conceded was so soft and it was really disappointing the manner we conceded from the free-kick," he said.
"Southampton are obviously a top team with top players but with the way the boys performed today, I was very proud of the efforts. We just couldn't see it over the line.
"We need to keep doing what we have been doing in the final four games. I'm disappointed to lose the game today and we will talk about all the other stuff [injuries to Clark and Murkin] another day.
When asked if he feels it is possible for Derby to still reach the play-offs, he added: “Of course it is. Anything can happen in football. We will just keep going and do what we do.
"We lost the game to a soft goal, came to a top team with a top team and we have to really believe that we can see it through now."
