St Mirren survived more than 54 minutes with 10 men to knock 2010 finalists Ross County out of the Scottish Cup at the second attempt.

Steven Thompson's deliberate elbow before the interval earned him an early bath but Nigel Hasselbaink's 52nd-minute finish proved decisive despite an ensuing spell of second-half pressure by the first division leaders.

A tremendous Gary Teale strike early on had set the tone for initial St Mirren control but County looked, for long spells, capable of capitalising on Thompson's rash act only to fail in the final third other than when Sam Morrow pulled a goal back two minutes after Hasselbaink scored.

Danny Lennon, the St Mirren manager, refused to comment on the Thompson sending-off, saying he had not seen the incident, but praised his players' battling spirit as they broke County's 18-game unbeaten run.

Lennon said: "I thought from start to finish, it was a very committed performance. We were up against it when Stevie Thompson was sent off so the boys dug deep. We'll look to try to take that same type of character into the next seven league games.

With his team's championship ambitions in mind, Derek Adams, the Ross County manager, made six changes from Saturday's draw at Raith. Joe Malin, the reserve goalkeeper, made his first start of the season ahead of Michael Fraser and there was no place for his captain, Richard Brittain. St Mirren made only one alteration from their scoreless draw with Motherwell as Hasselbaink replaced the cup-tied Dougie Imrie.

County threatened first when Mark Corcoran pounced on a slack pass and surged away from David Barron on the left. A decent cross was glanced well wide by Morrow.

Hasselbaink had two attempts blocked as play tore from end-to-end, but St Mirren went ahead after 14 minutes when Barron's cross was neatly knocked down by Thompson and Teale's fine strike flew low past Malin from 22 yards.

Hasselbaink went within a whisker of adding a second eight minutes later. Alert to a long punt forward, he wove through three defenders and lashed a left-foot shot just over.

However, just as Saints looked comfortably in control, Thompson, off the ball and in clear view of the assistant referee, swung an elbow in the face of Johnny Flynn, the County defender. After consultation, referee Bobby Madden sent him off.

Four minutes into the second half, the 10 men caused a scare with Teale's cross half-cleared by Corcoran only for Jim Goodwin to draw a fine diving save from Malin with a fierce strike.

However, they did add a second goal after 52 minutes when Graham Carey dribbled in from the left and found Hasselbaink who beat Malin easily from 10 yards.

County needed a swift reaction and it came when Rocco Quinn's free-kick on the far left picked out Morrow and he cracked a header in off the under-side of the crossbar.

Morrow then shot just over on the turn but although St Mirren were on the back foot they were comfortably soaking up County's best endeavours. Home substitute Alex Cooper did test Craig Samson with a stinging strike in the final minutes but St Mirren were not to be denied.

Adams seemed far from crestfallen after defeat. He said: "We made six changes and gave some of our players a rest. We have an important league campaign to take care of. I'm delighted with the players who came in and performed so well but unfortunately we didn't have enough to go through to the next round.

"We have to prioritise. We have eight games in 25 days and that's a lot of football. It's vital we move on in our league campaign. We didn't need a replay but it was good other players got a game.

"There was still good exp-erience in the side and I was disappointed we didn't do more against 10 men, but a few of out players tired, having not played so much."