Dundee made two changes from Saturday, Sam Fisher retained his place after replacing the injured Malachi Fagan-Walcott, and Charlie Adam returned to the starting 11 at the expense of Declan McDaid.
Dundee struggled in the first 15 minutes and gave the ball away too much, Ayr United took the lead on 17 minutes. A poor goal to give away after losing the ball 40 yards from goal. Dundee struggled for the rest of the half.
Second half and after they changed the midfield with Adam lying deeper it changed very little. Ayr doubled their lead after more slack play from the dark blues.
Changes were made when Declan McDaid and Osman Sow came on for Paul McGowan and Danny Mullen, followed by Jonathan Afolabi replacing Jason Cummings. The result was constant Dundee attacking, but it was all ineffectual.
Ayr wrapped up the points when they scored a third and Dundee did score with Osman Sow scored from close range.
A poor result and performance from the dark blues and they must pick themselves up for the visit to Alloa on Friday.
Dundee: Legzdins, Elliott, Ashcroft, Fisher, Marshall, McGowan, (McDaid 53), Anderson, McMullan, Adam (c), Mullen (Sow 53), Cummings (Afolabi 63). Unused Subs: Hamilton, Kerr, Byrne, Cameron.
Referee: Alan Newlands