Gretna's relentless march towards the league title continued here in fine style with a comfortable win.
First half goals from Kenny Deuchar and Steve Tosh ensured the game was over by half time, and the captain Chris Innes sealed it after the break.
Deuchar's early header from a Ryan McGuffie cross set the tone, and they were soon two up when Tosh's cross-cum-shot nestled into the top corner.
Ayr showed little resistance, and the table toppers stretched their lead early in the second half when Innes punished an error by trialist Jered Stirling to fire home.
United only came to life when the game was dead, and substitute Craig Conway gave them a boost. He crossed for Gareth Wardlaw to head wide before Raymond Logan twice went close.
Ayr finally did get a consolation when Chris Robertson headed down for Logan to fire home from six yards.
But it was too little too late and while Gretna go from strength to strength, I'ts game no. 11 without a win for Ayr.