The Newcastle United legend was far from pleased as he watched his former side concede goal after goal.
The former Newcastle striker watched on as City scored not once, not twice, but all of three times before half-time, putting John Carver's side to shame.
Perhaps having a meltdown of his own, Shearer expressed strong-worded outrage as Manchester City's first goal went in - and was still swearing as the third was scored.
According to Lineker, the Newcastle icon had calmed down by then, although his former club's performance had hardly improved...
Less than 30 seconds gone, Man C penalty. Shearer screams "my f**king God!"— Gary Lineker (@GaryLineker) February 21, 2015
3-0. Shearer no longer screaming. Just mumbling "f**k me"— Gary Lineker (@GaryLineker) February 21, 2015
Sadly, Newcastle's display against Manchester City was typical of a John Carver side. The current Magpies boss has sent out dull and dire teams on more than one occasion, having only registered one win during his time as manager so far.
Newcastle were facing a strong side in the Premier League champions but, as Shearer's outrage suggests, there was no excuse for the level of their own performance.
It will take a lot of work for the St James' Park outfit's season not to peter out now...