Reading led for much of the game thanks to Pavel Pogrebnyak's early goal, but had to settle for a 1-1 draw thanks to a late Cardiff City equaliser from Conor McAleny.
The away side came flying out of the blocks, but found themselves behind after just four minutes when Pogrebnyak converted from Gareth McCleary's cross.
Reading then felt that they should have had a penalty when the Russian striker went down in the box under the challenge of Bruno Ecuele Manga, but referee Scott Duncan waved away their appeals.
Cardiff's Joe Ralls skipped free of the home side's defence just after the restart, but could not test Adam Federici in the Reading goal.
The lively McCleary poked narrowly wide but should have done better after Manga's poor pass let him in, before another defensive howler - this time from Lee Peltier - almost allowed substitute Kwesi Appiah to double his side's lead.
Cardiff goalkeeper David Marshall then reacted well to turn Appiah's effort behind, and, from the resulting corner, Michael Hector headed against the frame of the goal.
However, with time running out, McAleny swept home against the run of play from close range to rescue a draw for the away side, who remain seven points above Reading in the Championship table.