With Colchester enjoying their FA Cup heroics against Derby, the Swans could have moved ahead of them on goal difference with a win but Louis Carey’s goal on the stroke of half-time ended that hope.
That allowed Huddersfield, who produced a stirring comeback from 2-0 down to beat Oldham, to overtake the Swans.
Chris Porter and Luke Beckett put the visitors ahead inside 33 minutes but Guy Branston’s own goal seconds before half-time lifted the Terriers.
Three minutes after the interval Pawel Abbott equalised and in the 59th minute David Graham gave Huddersfield victory.
Chesterfield remain seventh despite their 2-1 win at Bournemouth, where they took a 25th-minute lead through Wayne Allison.
James Hayter’s 66th-minute penalty briefly levelled matters before Jamie O'Hara secured the Spireites win.
Blackpool ran out 3-0 winners at Hartlepool, where both sides had a man sent off.The Seasiders’ Neil Wood was dismissed in only the 10th minute but Mickey Barron followed him down the tunnel 17 minutes later for a professional foul and from the resulting penalty Peter Clarke fired home.
Clarke scored another penalty in the 74th minute before Keigan Parker sealed things eight minutes from time.
Lee Williamson gave struggling Rotherham a 54th-minute lead at Gillingham only for the hosts to equalise through Gavin Grant. Tranmere’s trip to Bradford finished goalless.