Swansea City first-team coach Alan Curtis was left ruing individual errors after losing 3-2 at AFC Bournemouth on Saturday.
Max Gradel gave the home side a 37th-minute lead with his first goal since returning from a six-month injury lay-off, pouncing on a Lukasz Fabianski error.
A fine Modou Barrow goal restored parity, but Josh King put Bournemouth ahead again just after the break by beating Fabianski at his near post.
Gylfi Sigurdsson appeared to have salvaged a point just after the hour mark, but Steve Cook's late header secured an important win for Eddie Howe's men and left Curtis – standing in for the unwell Francesco Guidolin for the third game in a row – frustrated.
"We clawed ourselves back twice, but individual errors cost us. It's disappointing," he told reporters.
"We have been working on defending set-pieces, but they are still a bit of an Achilles heel for us.
"But today it was more about individual mistakes and players switching off. Overall, I felt it was two teams trying to play the game on the floor and I do not think either side had the ascendancy. The game was back and forth.
"At 2-2, I thought we might be able to go on and win it, but we conceded again, which was really frustrating. We have slipped up a little bit.
"A positive result today would have made it much easier for ourselves. It just means we need to work doubly hard between now and the end of the season."
Despite his frustrations with the result and some errors, Curtis was particularly pleased by the performance of Barrow, who was a livewire on the right flank and scored his first Premier League goal.
"I thought Mo [Barrow] was excellent today," he added. "He has made a huge impact from the bench recently and was due a start. He gave us an edge and a real threat going forward."
