Freddie Sears’s second goal in two games has given Town a 1-0 lead against Middlesbrough at half-time.
Cole Skuse, Cameron Carter-Vickers and Sears returned to the Blues’ line-up with the injured Mustapha Carayol and Ben Folami dropping out, while Luke Woolfenden moved to the bench.
Town again started with three at the back with Jordan Spence at right wing-back having overcome the knee injury which had made him a doubt going into the match.
Middlesbrough, who went into the game confirmed in the play-offs but looking to seal fifth spot, were unchanged from the team which beat Millwall 2-0 at home last week. Former Blues skipper Grant Leadbitter was on the bench.
Town started brightly and struck the first shot in the third minute, Martyn Waghorn screwing wide after exchanging passes with stand-in skipper Skuse, playing ahead of fellow midfielders Tristan Nydam and Callum Connolly, on the right of the box.
The Blues almost went in front via a freakish goal in the fifth minute when Waghorn scuffed a corner from the right and the ball hit the outside of Darren Randolph’s post.
Confident-looking Town continued to dominate and on seven Knudsen shot wide from distance.
And a minute later the Blues took the lead. Sears outmuscled Teessiders’ skipper Ben Gibson on the right, then brought the ball into the area before smashing a low shot beyond the diving Randolph’s right hand.
The striker gleefully celebrated his second goal in two matches, following on from a 38-game goal drought, in front of the tunnel with kit man James Pullen before the rest of the team joined in.
On 12 Skuse picked up the first yellow card for a game for a foul on Adama Traore, then - after Muhamed Besic had curled over for the visitors on the quarter hour - the midfielder scuffed a shot wide from distance.
Boro had got more into the game after Town’s goal and in the 22nd minute Ryan Shotton’s low cross from the right was deflected into the side-netting.
The Teessiders continued to dominate possession and were increasingly threatening to get on terms. On 34 Webster diverted Stewart Downing’s low cross only an inch or so wide of Bialkowski’s right post.
Tony Pulis’s side went close again from the resultant corner, Daniel Ayala stabbing a low effort from beyond the far post which Connolly cleared off the line.
The players briefly came off for a drinks break on 35 on what was a very warm Portman Road afternoon, then soon after they returned to the field Waghorn shot wide.
Boro seemed to lose their momentum following the delay, then just before the half-time break Nydam was yellow-carded for a foul on Traore and Sears joined him in the book for kicking the ball away.
Neither team threatened again before referee David Coote’s whistle signalled the end of the half, prompting applause from the Blues support.
Town had started strongly and grabbed their goal through a rejuvenated Sears. Boro came more into it after the goal and will feel they deserved to level but the Blues defended resolutely and on a couple of occasions desperately to maintain their lead.
Town: Bialkowski, Carter-Vickers, Webster, Knudsen, Spence, Skuse (c), Connolly, Nydam, Kenlock, Sears, Waghorn. Subs: M Crowe, Gleeson, Hyam, Morris, Cotter, Woolfenden, McLoughlin.
Middlesbrough: Randolph, Friend, Ayala, Shotton, Gibson (c), Clayton, Assombalonga, Howson, Downing, Besic, Traore. Subs: Konstantopoulos, Fabio, Leadbitter, Bamford, Cranie, Fry, Harrison. Referee: David Coote (Nottinghamshire).