The lifelong Wednesdayite tweeted the message yesterday afternoon the day before the Blades’ all important tie with Ipswich Town.
He said he wanted to get the good luck wishes out of the way before his timeline became ‘unbearable’ over the weekend.
United manager Chris Wilder had done an ‘incredible job’, he added, and if they were to be promoted – as looks likely – they would deserve it.
Being so complimentary to his team’s biggest rivals took it out of him however, and he joked he would have to go for a lie down after Tweeting it.
Messages under the Tweet from Owls and Blades alike all agreed with him – with Wednesday fans understandably grudging in their praise and United fans nervously waiting for the celebrations to start.
United fan Rob Dyson said: “Thanks top man. We’re not there yet but I’ll accept your heartfelt congratulations for a top season and top manager.”
Mosborough Blade said: “I know that hurt Peter but well done.”
Ems 1867 said: “I want to like this, but I'm struggling. Not such an arse that I cant acknowledge they've done well though - fair play to them.”
And Wednesday fan Santero said: “It's too depressing, but you're spot on.”
Sheffield United take on Ipswich Town at Bramall Lane at 5.15pm today.
Their automatic promotion rivals Leeds United take on Aston Villa at Elland Road tomorrow.