Millwall pulled off a stunning upset last night when they defeated play-off chasing Birmingham City 2-0 at St Andrew’s.

The win was only the Lions’ third on the road this campaign and moved them ahead of Wigan and Reading in the table.

Neil Harris’s side do not play this weekend in the league due to their continued involvement in the FA Cup as they face Brighton and Hove Albion at The Den at the quarter-final stage.

But that was not the focus last night, league matters were, and Millwall came with a game plan and executed it to perfection in the Midlands.

It was not a particularly attacking display from the visitors but more of a counter-attacking performance with the formation set up for precisely that tactic.

In fact, Harris’ boys were clinical - scoring twice from two shots on target.

And the goals came from an unlikely source in Ben Thompson.

The 23-year-old opened the scoring after just 13 minutes and doubled his tally and his side’s advantage just after the half-hour mark.

His influence was mainly in front of goal, but he was a key figure in the defensive resiliency the Lions showed on Wednesday evening.

Thompson played the entire game from start to finish and was the only member of the Millwall side to have a shot on target – scoring with both his efforts on goal.

Being away from home, Harris would have expected to see less of the ball and turned out to be the case, as he managed just 3.4 per cent possession during the game – equating to 46 touches of the ball.

Thompson is a grafter; he will battle and claw in the midfield but has the energy and the pace to burst forward.

The all-action Lion was at the heart of most things defensive-wise and was forever closing his man down and chasing back when needed.

It was a performance beyond his years and one that has been consistent since his return to the side in January after a loan spell at Portsmouth.

He managed to complete 18 of his 26 passes, a percentage of 69.2 during the course of the game.

Such was the defensive display from Millwall; he didn’t feature in any of the top five in any passing statistic for the fixture.

He did, however, win both tackles he attempted and 31 per cent of aerial duels which is impressive considering he as the smallest player on the pitch by some distance yet manages to leap like a salmon at will.

Thompson’s influence was evident in front of goal and doing the dirty work in the midfield.

It was a colossal performance and one that he and the team can take heart from going into Sunday’s cup tie and the rest of the season.