Reading substitute Modou Barrow's stoppage-time goal condemned strugglers Ipswich to a 2-1 defeat.
The battle of the basement clubs was billed as a must-win game for the Tractor Boys and they are now 12 points adrift of safety.
Norwich loanee Nelson Oliveira opened the scoring for The Royals in the 19th minute with Gwion Edwards replying for Ipswich in the 83rd.
But the sting in the tail came from Barrow who was sent clear following a late break by Reading to beat Ipswich keeper Bartosz Bialkowski.
Oliviera was the first player to go into referee Geoff Eltringham's book in the 13th minute following his complaints that he was fouled in the penalty area by Ipswich goalkeeper Bialkowski.
But the striker, who was continually being barracked by the Ipswich fans because of his Norwich connections, scored in the 19th minute to give the visitors the lead. It came after Garath McCleary was put clear down the left and his pass to the unmarked Portuguese was cleanly dispatched into the Ipswich goal.
A minute before the break neat work from Collin Quaner in the Reading penalty area almost led to an Ipswich equaliser. He fed the ball to Teddy Bishop who in turn passed to Jon Nolan free just outside the six-yard box but his shot was scrambled clear by the Reading defence.
And the last action of the half saw Bialkowski get his body behind a corner to the near post from Swift preventing it from crossing the goal line.
Ipswich manager Paul Lambert rung the changes at half time bringing on Cole Skuse and Edwards for Trevoh Chalobah and James Bree.
Ten minutes into the second period Toto Nsiala, who came on five minutes before the break to replace James Collins, made a run out of defence and passed to Alan Judge. The midfielder's goal-bound shot was parried by the Reading keeper and the midfielder claimed to be fouled in the penalty area with his follow up attempt, but his appeals were turned away by the referee.
A cross from Edwards in the 69th minute was nearly deflected into the Reading goal by defender Andy Yiadom but keeper Emiliano Martinez was alert to save the ball ending up in the visitors' net.
But the home side drew level in the 83rd minute when Edwards latched onto a speculative shot from Quaner to fire the ball into the net with a crisp right-footed shot from just inside the six-yard box.
With time running out, Barrow was clear on goal to comfortably beat Bialkowski with a last-gasp winner.
