Pop star-turned-country singer Jessica Simpson has apologized to fans for forgetting lyrics during a show in Michigan on Thursday night.

The star left fans stunned when she stumbled through her performance at the Van Andel Arena in Great Rapids, mumbling her lyrics, forgetting words and fighting back tears during a 38-minute set, supporting country trio Rascal Flatts.

According to one local concert reviewer, Simpson stopped the show at one point and asked her band to start a song again.

She apologized onstage, by mouthing the word "sorry" to fans, and on Friday, her publicist declared she just had "an off night". Her rep says, "She's a perfectionist and wanted to start some songs over."

The concert comes as Simpson's apparent weight gain makes headlines in the tabloids, after the singer was photographed looking bigger at a recent show.

It's not the first time critics have targeted Simpson for her forgetful nature onstage - she was ridiculed after botching Dolly Parton's "9 To 5" hit during a tribute to the country legend at the Kennedy Center in Washington, D.C. in December, 2006.

(This news article provided by World Entertainment News Network)