Bryan Robson warned his players that managerless meant dangerous and the prediction turned out to be only too accurate as Argyle deservedly ended United’s six-match unbeaten run to record their first win in 69 years at Bramall Lane and edge into the playoff places.

Argyle passed the ball well, made chances and hit the bar twice and it took top-drawer saves from United keeper Ian Bennett to defy them, their pace a telling factor on the break in the second half as they defended a lead given to them by Peter Halmosi.

It was a Hello-Goodbye moment for their assistant manager Tim Breacker, in charge after the defection of Ian Holloway to Leicester in midweek. It could be the first and last game of his reign, with Paul Sturrock expected to return to Argyle from Swindon.

The players and Breacker received good luck calls from Holloway before the game but the caretaker confessed: “I’ve told the players I don’t know if I’ll see them on Monday morning. I’ve enjoyed the day immensely and I’ve told them that, they showed the right attitude and that is very important to me.”

Argyle have taken 18 points from the last 30 and Halmosi, who won his 17th cap for Hungary in midweek, was the key. He took a 25th-minute chance superbly to put Argyle in front then hit the bar before half time and headed a Danny Webber effort off the line in the second half.

Breacker added: “We would be higher if we had had a bit more luck. The players have had a difficult week but coped very professionally.” Argyle looked more dangerous from the start, with the pace of Barry Hayles and Sylvan Ebanks-Blake a menace, and it proved no illusion as they made the breakthrough courtesy of Halmosi, the midfielder driving a 12-yard chance in off a post.

Bennett had to save from Hayles in the 36th minute and Ebanks-Blake a minute before the break, with Halmosi hitting the bar from 25 yards.

Nick Montgomery hit the outside of a post for United but Argyle produced the almost perfect response as Ebanks-Blake fired a bullet against the bar from 30 yards.

Robson was not happy and said: “In the first 25 minutes we had no urgency and no direction for whatever reason and that’s why we lost the game. There are no excuses, you can’t start at halfpace and then expect to be able to increase the tempo later. “

Credit to Plymouth, they could have had a couple more goals before we got going. I thought we had turned the corner but this was the most disappointing performance since I came here.” That does Breacker a lot more good than it does Robson.

Star man: Peter Halmosi (Plymouth)

Player ratings. Sheffield United: Bennett 7, Bardsley 6, Cahill 7, Kilgallon 6, Naysmith 6, Gillespie 5 (Tonge 58min 5), Montgomery 7, Armstrong 6, Carney 6 (Sharp 58min 5), Webber 7, Beattie 6

Plymouth: Larrieu 6, Connolly 6, Doumbe 7, Seip 7, Hodges 6, Halmosi 8 (Sawyer 77min), Nalis 6, Norris 7, Martin 7, Hayles 7 (Easter 86min), Ebanks-Blake 7