Peterborough capped a memorable week by claiming bragging rights with a 1-0 win at managerless arch-rivals Cambridge.
Having reached the EFL Trophy final on Tuesday, Posh grabbed the decisive goal 10 minutes into the second half.
In a seemingly unthreatening position, Ephron Mason-Clark delivered a cross from the left which evaded everyone in the box before finding the far corner of Jack Stevens’ net.
Their pressure had been building before half-time, with Archie Collins clipping the top of the bar from the edge of the box and the unmarked Kwame Poku somehow firing Malik Mothersille’s cross wide.
The hosts – who saw manager Neil Harris leave this week to return to Millwall – threatened themselves, with Jed Steer saving well from Jack Lankester’s effort and from the resulting corner Elias Kachunga headed in before being denied by the offside flag.
Having scored the opener, Mason-Clark nearly turned provider but substitute Hector Kyprianou thumped his effort onto the bar before Joel Randall’s shot was deflected just wide.
Cambridge’s big chance to equalise came on 80 minutes but Danny Andrew fired narrowly wide from 20 yards.