Johnson hands Sunderland victory
The 26-year-old England international followed up impressive individual displays in the cup victories over Carlisle and Manchester United to play the key role in a precious 4-1 victory at Craven Cottage.
Johnson gave the visitors a 23rd-minute lead with a fine free-kick and then set up fellow midfielder Ki Sung-Yueng to double his side's advantage with a deflected 41st-minute shot.
Steve Sidwell headed Fulham back into it seven minutes after the restart, but Johnson added a second with 21 minutes remaining and then converted and 85th-minute penalty to make sure the points headed back to Wearside.
Carlton Cole's 42nd-minute strike gave the visitors a half-time advantage, and although the visitors had to play out the closing stages with just 10 men after defender James Tomkins was sent off for a second bookable offense, midfielder Mark Noble added a second in injury time.
The Hammers climbed out of the bottom three by virtue of their win with the Bluebirds slipping below them to leave new manager Ole Gunnar Solskjaer in little doubt as to the task he faces.
The England international's 66th-minute strike did the trick on a day when the Saints dominated possession, but had to fight all the way to the whistle.