Championship Review: Martin reaches landmark as Bournemouth slip up
Steve McClaren's men have now won three consecutive league matches and came through a hard-fought contest against one of their promotion rivals at Portman Road.
Ipswich had lost just once at home in the second tier this term, but fell to Martin's strike before the hour - the Scot taking advantage of a loose Tommy Smith header to ensure maximum points for the visitors.
McClaren's side saw out a nervy finale when John Eustace was shown a second yellow card, but Martin's landmark goal, coupled with Bournemouth's reversal against Norwich City, tightens things at the summit.
Eddie Howe's side led at the Goldsands Stadium through Matt Ritchie's early opener only for Gary Hooper to level before the break for a Norwich outfit led by Alex Neil for the first time.
Neil was appointed Neil Adams' replacement at Carrow Road on Friday and would likely have taken a point when Jonny Howson was sent off after the hour.
However, Cameron Jerome inflicted Bournemouth's first league defeat since September, with Neil telling reporters: "It's fantastic for the lads and for me. We were resilient, worked hard and got the three points."
Brentford and Watford swap places inside the play-off spots after the former beat Rotherham United 1-0, while the latter fell to a 3-1 defeat against Huddersfield Town - late goals from James Vaughan and Joel Lynch enough for the Yorkshire side.
At the other end of the table, former Huddersfield skipper Peter Clarke helped bottom side Blackpool compound fellow strugglers Millwall's woes as the defender scored the winner at Bloomfield Road.
Wigan Athletic were downed by a Clayton Donaldson hat-trick at St Andrew's in a 3-1 defeat, while Eidur Gudjohnsen's first Bolton Wanderers goal since May 2000 denied Leeds United in a 1-1 draw.
Brighton and Hove Albion marked Chris Hughton's first league game in charge of the club with a win - Rohan Ince ensuring a 1-0 victory over Charlton Athletic - while Sheffield Wednesday increased the pressure on Nottingham Forest boss Stuart Pearce with a 2-0 success.
Cardiff City were back in their traditional blue kit as Sean Morrison fired the Welsh club to a 1-0 victory over Fulham with Reading and Middlesbrough ending goalless.