Dundee boss Paul Hartley criticised his players for a below-par display in a home defeat to Kilmarnock.
The visitors won with goals in either half from Josh Magennis and Steven Smith.
Rhys Healey headed home for the hosts with 14 minutes left, then goalkeeper Jamie MacDonald produced a great save to deny Dundee’s Paul McGinn an equaliser with a point-blank header.
Hartley said: “There are no excuses. We were just flat. We didn’t start playing until about 15 minutes from the end.
“We were second best for all of the first half and the better team won. I don’t know why it was like that.
“We had worked all week on how we wanted to play but we just didn’t carry it out. We had people under-performing and just didn’t play as a team.
“Now we have to get back on to the training ground and work hard. We’ve got Inverness next and have to look to get a positive result against them.”
Kilmarnock manager Gary Locke said: “This was our best away performance of the season. So all credit to the lads. I’m really just delighted for each and every one of them. We were excellent for 75 minutes to be fair.
“But then a bit of slackness led to their goal and then we were left hanging on near the end.
“But this is a difficult venue, so we’re very happy to come away with the three points.
“It was a great save from Jamie, who didn’t have a lot to do. It was one save today and he’s come up with the goods.
“We’re on a good run and Dundee are a good team, so we should be happy with our efforts.”