United didn't play well in the first half, but improved after half-time substitutions. But Kingsley Banks was in fine form and made a number of saves, aided by the woodwork.
An unmarked Pollard scored after 24 minutes, and a mistake by Mark Jones allowed James to make it 2-0 on 40 minutes.
United's constant pressure eventually paid off when Malcolm Ndekwe reduced it to 2-1 after 75 minutes, but with United pushing up to level, Greene broke clear to wrap things up on 80 minutes.
