Eli Manning threw four touchdown passes and enjoyed his best performance in more than a year as the New York Giants thrashed the Washington Redskins 45-14 last night.

Manning had not produced a four-touchdown effort since the first game of last season. He finished with 300 passing yards and also scored a rushing touchdown in the fourth quarter.

"His confidence has risen and his confidence in his team has risen," Giants' coach Tom Coughlin said of Manning and the quarterback's development in new coordinator Ben McAdoo's offence.

Receiver Victor Cruz had six catches for 108 yards while the running game churned out 154 yards on the ground.

Giants' tight end Larry Donnell was Manning's preferred target in the first half when he caught three touchdown passes to give New York a 24-7 lead.

Washington opened the second half with a 20-yard rushing score by Alfred Morris, but New York then capitalised on turnovers to close the game with 21 unanswered points.

Washington quarterback Kirk Cousins, who thrilled fans last week against Philadelphia, gave away four interceptions and also had a fumble.

"We were abysmal offensively and defensively," said Redskins coach Jay Gruden. "(Kirk) was trying to create a spark, and there was no spark there and he just forced a few throws.

“By no means can we put the blame on Kirk for this game. This was a total team debacle.”

The Giants lost their opening two games this season but things are beginning to look brighter thanks to the play of Manning.

The two-time Super Bowl champion endured possibly his worst season in 2013 when he tossed a league-high 27 interceptions.

Manning got off to a similarly slow start this season, but has thrown six touchdowns and just one interception in their last two victories.