Pedantic twat alert, but the defeat to Cov (in which Asa Hartford was sent off just after we got it back to 2-1 for twatting their full-back Danny Thomas off the ball, thus sabotaging our chance of a comeback) was actually in the fourth round.
In the third round, we beat Cardiff City 3-1 at Maine Road in a match notable for Tony Book's return after he became assistant manager at the Welsh club. IIRC, we'd also sold Dave Bennett to Cardiff the previous summer and I think he played (can't remember whether his brother Gary, who we let go on a free and also signed for Cardiff, was in the side as well), as did ex-City 'keeper Ron Healey.