John Eustace said his Derby County side were made to work for victory over Swansea City because the Welsh side are going back to their old way of playing.
Derby climbed into the Championship play-off places courtesy of Saturday's 2-0 win over the Swans.
Both goals came from Callum Elder corners in the second half, with Rhian Brewster netting against his former club before Patrick Agyemang made the points safe with a powerful header.
Swansea had dominated the first period and continued to control the flow of the contest for a spell even after Brewster's opener.
But for all their possession, Vitor Matos' team lacked menace in the final third, meaning Derby's set-piece threat proved decisive.
"It was a hard afternoon," said Rams boss Eustace.
"They are really back to playing the old Swansea way now, dominating possession [with] lots of real good footballers."
Swansea had 72.2% of possession at Pride Park, as well as more shots, more touches in the opposition box and a higher xG than their hosts.
"They can hurt you if you are not disciplined enough," Eustace added.
"But we showed good discipline. We didn't get too disappointed in giving too much of the ball away and I knew as the game opened up we'd have more opportunities on the transition and we'd be able to hurt them on set-pieces."