Elsewhere, Coventry held on against Morecambe, Harrogate Town and Hastings United must replay and Oldham come from behind to beat Doncaster Rovers in the second half
|FA CUP 2nd ROUND RESULTS
|HARROGATE TOWN||1-1||HASTINGS UNITED||CREWE||0-1||BURTON ALBION|
|COVENTRY||2-1||MORECAMBE||SHEFFIELD UNITED||2-1||PORT VALE|
Sheffield United survived a scare at Bramall Lane as they were 1-0 down to League Two side Port Vale until injury time, when Shaun Miller netted a quick fire double to send his side into the third round of the FA Cup.
Crawley Town had no problems in disposing of 10-man Chelmsford as they strolled to a 3-0 victory courtesy of goals from Nicky Adams, Billy Clarke and a late penalty from Gary Alexander.
League One leaders Tranmere struggled against Chesterfield of League Two, going 1-0 down after 31 minutes through a Liam Cooper goal, but a goal either side of half-time took Rovers through.
Burton Albion's one-goal victory over Crewe Alexandra proved to be the biggest shock result as the League Two side held on to the lead which was gifted to them by Calvin Zola after only 5 minutes.
Ryman Premier League Hastings United made the third round draw but are still to play Harrogate again after they drew 1-1 at Wetherby Road.
Coventry put an end to League Two side Morecambe's FA Cup run with a Gary McSheffrey penalty and a Carl Baker strike in the 46th minute.
A goal each after in stoppage time for Accrington Stanley and Oxford United meant they finished 3-3 and will also have to go to a replay in order for one of them to progress to the third round.
There was more last-minute drama between Lincoln City and Mansfield Town as Matt Rhead scored in injury time for Mansfield to seal a replay.
Two goals in the first half for Preston sees their FA Cup dream live on as they beat League Two's Gillingham comfortably 2-0.
Blue Square South side Dorchester struggled in the first half against Luton and were unable to force a replay despite a goal late on, with Luton victorious 2-1 and though to the third round.
Elsewhere, Barrow's fixture against Macclesfield was postponed due to a frozen pitch. No new date has been set for that game as of yet.