Carlisle United and Cardiff City will be playing for the right to face Reading in the FA Cup Fourth round.
The Royals beat Blackpool 2-0 in their Third Round replay.
That means the Championship side will host either the Cumbrians or Cardiff, who meet at Brunton Park tomorrow night.
Goals in either half at Bloomfield Road from Lucas Boyé and Jordan Obita secured victory for Mark Bowen's side.
If United get through it will be their first-ever trip to the Madejski Stadium, and a first meeting with the Berkshire outfit since 1982.
In League Two, meanwhile, Carlisle's cushion above the relegation place was reduced to six points tonight.
Bottom side Stevenage drew 0-0 with Oldham, while second-bottom Morecambe beat Port Vale 2-1 thanks to a winner from ex-Blues striker Cole Stockton.
United now have a game in hand on both Morecambe and Stevenage.
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