Sir Alex Ferguson was denied a winning send off into retirement as West Brom roared back from three goals down to snatch a 5-5 draw in a quite staggering 10-goal thriller against Manchester United at The Hawthorns.
Romelu Lukaku hit a hat-trick for the Baggies, who came back from 3-0 down, and James Morrison and Youssouf Mulumbu were also on target.
Kagawa put United ahead from Hernandez's cross and moments later Antonio Valencia found space out wide before drilling a low shot across the six-yard box which the hapless Jonas Olsson turned into his own net.
When Buttner strode onto Tom Cleverley's pass and drove his first goal since September into the bottom corner, plenty of home fans headed for the concourses even though there was less than a third of the contest completed.
But Morrison managed to pull one back just before the interval and substitute Lukaku struck immediately afterwards.
Order was quickly restored though as Valencia crossed for Van Persie to put the seal on a second successive Golden Boot title, the difference being that this year, the Dutchman has a team prize to go alongside it.
By now the game had seen the introduction of Ryan Giggs, for his 941st appearance under Ferguson, and the veteran Welshman quickly crossed for Hernandez to touch home.
But West Brom refused to surrender and first Lukaku, then Youssouf Mulumbu scored to give the scoreboard as surreal a look as the number of years Ferguson has been manager.
That old competitive instinct resurfaced as the Scot demanded to know how long was left. Not long enough was the answer as Lukaku scored the final goal to take some of the sheen off Ferguson's day.