Rangers slipped up at the top of the Scottish Premier League on Sunday, losing 1-0 to Kilmarnock at Rugby Park.
Ally McCoist's men were seeking their 15th consecutive away victory but were undone by Manuel Pascali's late strike, leaving them just four points clear of Celtic.
Cameron Bell saved well from Nikica Jelavic early in the game, before the Croatian saw another effort come back off the post.
As Rangers poured forward, Bell saved brilliantly at the feet of a frustrated Steven Davis.
Killie had a penalty claim ignored when Gary Harkins went to ground under pressure from Ross Perry and Kirk Broadfoot but referee Alan Muir was unimpressed.
James Fowler hooked an Aluko drive off the line, before Allan McGregor came to the rescue of Rangers with an excellent save after finding himself one-on-one with Racchi.
McGregor, however, could do nothing with the winner.
A corner broke to James Fowler and he punted into the path of Pascali who nodded into the back of the net, with Sone Aluko coming off the line and playing the Italian onside.