Marko Arnautovic helped fire West Ham into the FA Cup fourth round with a 2-0 win over Birmingham.
But the Austrian forward was far from happy at being substituted after only 20 minutes at the London Stadium.
Andy Carroll, who had replaced Arnautovic, eventually sealed West Ham's passage with his first goal of the season in stoppage time.
It had taken less than two minutes for Arnautovic to give the hosts the lead, reacting quickest to nod home after Angelo Ogbonna's header was parried by Blues keeper Lee Camp.
However, Arnautovic's afternoon ended prematurely soon after when his number went up on the electronic substitutes' board.
Arnautovic may have picked up a slight knock, but he clearly felt it was not going to be a problem and wanted to continue.
However, with Arsenal the visitors next weekend, Hammers boss Manuel Pellegrini was taking no chances with his star man, who had only just returned from a month out injured.
In bizarre scenes, Arnautovic continually shrugged 'why' as he trudged off, had a lively discussion with Pellegrini on the touchline and stopped in front of the bench to question the medical team before disappearing down the tunnel.
The 29-year-old has a face like thunder at the best of times, but even he still looked annoyed when he eventually took his seat in the dugout.
Anthony Knockaert's crisp strike helped Brighton cruise past Bournemouth 3-1 and into the FA Cup fourth round for the ninth time in 10 seasons.
Yves Bissouma and Florin Andone wrapped up the Seagulls' comfortable Dean Court victory, with both sides making sweeping changes from midweek Premier League exertions.
Knockaert's first goal in 12 games set Brighton en route to another fourth-round tie, with Bissouma bagging his maiden Seagulls strike and Andone his third of the campaign.
Marc Pugh's classy strike briefly had Bournemouth thinking of a second-half comeback, with the midfielder notching his first Cherries goal since August 2017.
But when Andone nodded in after a messy Brighton corner, the game was up.
Here are the full list of results from the FA Cup third round 12.30pm kick-offs:
Bournemouth 1-3 Brighton
Burnley 1-0 Barnsley
Man United 2-0 Reading
Sheffield Wednesday 0-0 Luton
Shrewsbury 1-1 Stoke
West Brom 1-0 Wigan
West Ham 2-0 Birmingham
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