Dave Grohl Takes Shot at Taylor Swift, Implies She Doesn't Perform Live

Dave Grohl's ready to Foo Fight some Swifites ... 'cause he took a shot at Taylor Swift -- implying she's not actually performing live at her shows.

The singer-songwriter took the stage with the Foo Fighters at London Stadium Saturday night ... about 25 miles from Wembley Stadium where Taylor has performed all three of her shows this weekend.

Check out the clip ... DG starts out by name-dropping the pop star's "Eras" Tour -- which receives a lot of boos from the crowd. Dave jokes FF should rename their string of shows the "Errors" Tour 'cause he says they've messed up their fair share since hitting the road.

Then Dave goes for T-Swift's throat ... saying errors are bound to happen when you actually play live music -- implying Taylor doesn't and receiving applause from the fans.

Unclear exactly why Dave's firing off at Taylor here ... especially since he's praised Swift in the past, saying back in 2015 he's totally obsessed with Swift -- and even dedicating one song to her at a music festival they played that year.

Sounds like Dave's feeling rather differently these days though ... and, ya gotta wonder if he's just trying to make his audience laugh or if there's animosity here.

BTW Taylor's clearly not sweating Dave's comments -- 'cause she's living it up with the man of her dreams in London ... bringing Travis Kelce out onstage during her third and final concert at Wembley Sunday.

We've reached out to Grohl to clarify his comments ... so far, no word back -- but, sounds like the pop-rock war's about to kick off.