DANNY JOY AS ROYALS PULL AWAY.
DANNY WILLIAMS' goal saw Reading open up a five-point lead over Forest in the race for the play-offs.
But a miserable display by Charlton left them sweating, just two points above the drop zone.
Good football was in short supply. But the Valley's bumpy surface cannot be blamed for so many misplaced and overhit passes, with Charlton's Callum Harriott the main culprit. The Addicks have scored only 27 league goals this season - the fewest in the Championship - and a below-par Reading easily dealt with the home team's powder-puff forward line.
The decisive goal came in the 73rd minute when Davide Petrucci, who had been on the field only six minutes, was caught in possession on the edge of the Royals' penalty area.
A classic counter-attack ended with Danny Guthrie passing to Williams, who struck a rising 12-yard shot beyond Ben Hamer.
Relieved Reading boss Nigel Adkins, whose side have won five of their last six away matches, said: "We knew it would be a challenge and we were prepared for that. We came away from home and won again with a clean sheet.
"We were better in the second half when the momentum was with us. We've scored some massive counter-attacking goals and Danny scored an excellent goal today. There is a spirit and confidence about the players and we have another huge challenge on Tuesday against Bournemouth."
Charlton came into the game on the back of three wins in their last five matches. Apart from not scoring, the home team created few chances and manager Jose Riga said: "For an hour we were comfortable, even though hardly any chances were created by either team.
"Reading have good organisation and are good on the counter. We deserved at least one point and one mistake cost us, but that's football."
Statistics do not always tell the full story, but the fact that in the first half there was only one shot on target - and that a scuffed effort - underlined how poor the opening 45 minutes were.
On 21 minutes Jordan Cousins was clear in the penalty area after beating his marker, but the midfielder sliced his shot, which golkeeper Alex McCarthy saved easily.
Reading showed more urgency in the second half and two minutes after the interval Adam Le Fondre crossed to Williams.
The German-born United States international's shot was so wide it almost went for a throw-in.
Five minutes later, when Charlton only half-cleared the ball, Williams' volley was off target. Charlton replied with a low shot by Rhys Wiggins which did not trouble McCarthy.
The first real goalscoring effort came in the 61st minute when Hamer leaped to palm Guthrie's 30-yard free-kick over the bar.
After Williams made up for his previous misses with the winner Reading were happy to sit back, confident they could handle Charlton's impotent attack.
CHARLTON: Hamer 7 - Wilson 6, Morrison 7, Dervite 6, Wiggins 5 - Harriott 5, Cousins 7 (Obika, 82mins), *POYET 8, Jackson 6 (Petrucci, 67mins, 4) - Ajdarevic 5 (Reza, 58mins, 5) - Church 5.
READING: McCarthy 7 - Gunter 7, Pearce 7, Gorkss 7, Obita 6 - Williams 7, *GUTHRIE 8, McAnuff 7, Drenthe 5 (McCleary, 64mins, 5) - Pogrebnyak 6, Le Fondre 6 (Robson-Kanu, 76mins).
REFEREE: K Hill 6.
WATER LET DOWN: Jose Riga
HUG A GOODIE: Reading fans celebrate with Danny Williams