The U’s pressed hard from the start against Peterborough United, and while they didn’t gain an early lead, they persevered in the second half and nudged in front thanks to Elliott Moore’s header nine minutes after the break.
Naturally, the Posh then grew into the tie and began to pen United further and further back.
The U’s defence held firm though, and limited the visitors to no genuine chances of serious note.
United head coach Buckingham said: “It’s an advantage, but we’re only halfway through. I’m happy with what I’ve seen tonight.
“In the first half, I thought we were very good, and in the second half, there were a few things we need to tidy up on going to their place on Wednesday.
“To come away with an advantage was important because they’re a very good team. We saw that when we played them at their place, and the last two occasions when we played them. I’m sure Wednesday will be a very tough challenge for us.
“If we can take the energy levels and the understanding of what we’re trying to do, the way I’ve just seen tonight, then I’ll be very happy.
“We’ve got a way we want to play. We want to play exciting football and get at teams. We want to come into these types of games, and try and win.
“Of course there are moments in games where you can’t continue that all the way through, especially when you play against a very good Peterborough side, who have very dangerous players and a manager who’s had a lot of success.
“There are always going to be moments in the game when you need to weather a bit of a storm, and I thought they gave as good as they got in the second half.”