Brad Friedel had been key to Blackburn going in at half-time on level terms and the Rovers goalkeeper continued to defy Liverpool after McCarthy's goal.
Friedel saved well from Dirk Kuyt, though he was rescued by the woodwork, when Xabi Alonso's shot hit the post.
Liverpool will wonder how they went away with nothing from this game, but that they did had much to do with Friedel's heroics.
The American enjoyed a miserable spell at Anfield between 1997 and 2000, but he has flourished since joining Rovers.
If Blackburn rode their luck at times, there was nothing fortunate about their second-half display as they unsettled Liverpool out of their passing game.
Liverpool's loss of composure was illustrated when Alonso was rightly booked for a horrible tackle on McCarthy after the South African had skipped past a couple of tackles.
Liverpool's defeat marked an unhappy return for former Blackburn striker Craig Bellamy, who was making his first return to Ewood Park since his summer move to Anfield.
Bellamy's movement was as ever exemplary and although he was eventually replaced by Luis Garcia he was one of more Liverpool's impressive performers.
Bellamy came close to giving Liverpool the lead when he got on the end of a flowing move involving Alonso and John Arne Riise, but the Liverpool striker's shot went the wrong side of the post.
Bellamy has forged an effective partnership with Kuyt in recent games, but with the Dutchman rested, Crouch was chosen to link up with the Welshman.
Crouch missed two headed chances, the first time putting the ball straight at Friedel, though for the second one the Liverpool striker forced the Blackburn keeper into a good save.
Having negotiated the opening 45 minutes, Pedersen and McCarthy combined to put Blackburn ahead just after the break.
The move was started by a delightful piece of skill from Tugay, whose stepover took him away from Steven Gerrard, before the Turkish midfielder released Pedersen, whose inviting cross was sidefooted in by McCarthy.
Benitez did not wait long to replace Crouch with Kuyt and the former Feyenoord striker's arrival reinvigorated the Liverpool attack.
The Dutchman forced a reaction save from Friedel, who was then beaten by a swerving shot from Alonso, which thudded against the post.
Alonso was soon turning away in frustration for a second time when another shot was brilliantly pushed away by the former Liverpool goalkeeper.