Coventry City are now further adrift after their 1-0 defeat at Peterborough United.
City, who are bottom of the table, are now six points behind Doncaster Rovers who came from a goal down to beat Leicester City 2-1 with a brace from Billy Sharp.
City are now eight points adrift of third from bottom Nottingham Forest who drew 0-0 at 21st placed Bristol City.
Millwall dropped to 20th after a 2-0 defeat at Hull City whilst Ipswich went above them with a 1-0 win over Derby County.
West Ham joined Southampton at the top of the table with a 1-0 win over Barnsley at Upton Park, whilst Middlesbrough are third after coming back from goals from former Coventry City duo Ben Turner and Aron Gunnarsson to win 3-2 at Fifith placed Cardiff City.
Leeds are stil sixth despite a 1-0 home defeat by Reading and Blackpool are eighth after a 0-0 draw against Watford..