Chris Boswell of the Pittsburgh Steelers watches his game-winning field goal against the Indianapolis Colts during the second half at Lucas Oil Stadium on November 12, 2017 in Indianapolis, Indiana

Los Angeles (AFP) - Chris Boswell drilled a last second field goal to give the Pittsburgh Steelers a fourth straight victory on Sunday as the Minnesota Vikings held off the Washington Redskins to maintain their winning streak.

Boswell’s 33-yard effort gave Pittsburgh a comeback 20-17 win over the Indianapolis Colts which saw the Steelers move to 7-2 at the top of the AFC North.

It was the final act of a second half revival by the Steelers, who had trailed 17-3 in the third quarter before rallying to overturn the deficit.

Steelers quarterback Ben Roethlisberger helped set up the game-winning field goal after finding Antonio Brown with a 32-yard pass with 35 seconds left at the Colts’ Lucas Oil Stadium.

Roethlisberger had earlier found tight end Vance McDonald for a touchdown before picking out Martavis Bryant with a two-point conversion to tie the score at 17-17.

Elsewhere Sunday, Minnesota improved to 7-2 at the top of the NFC North with a 38-30 victory in Washington.

Vikings quarterback Case Keenum threw a career-high four touchdown passes while Adam Thielen amassed 166 receiving yards to help set up the win.

The Vikings had appeared to be cruising to a comfortable win after opening up a 35-17 lead early in the third quarter.

But a Washington fightback saw them close to 35-27 early in the fourth quarter after a Nick Rose field goal and a Kirk Cousins touchdown from two yards out.

The Vikings however were given breathing space when former Redskins kicked Kai Forbath nailed a 53-yard field goal to make it a two-score game at 38-27.

The Vikings defence then stopped Washington on a fourth-and-one drive to effectively seal the win.

New Orleans meanwhile cemented their status as one of the form teams of the NFC after clinching a seventh consecutive victory in a 47-10 rout of the Buffalo Bills.

Running back Mark Ingram II rushed for 131 yards and three touchdowns as the Saints, unbeaten since losing their opening two games of the season, improved to 7-2 to lead the NFC South at New Era Field.

Rookie Alvin Kamara also rushed for 106 yards and a touchdown while another rookie Trey Edmunds had a 41-yard gallop to score in the fourth quarter.

Quarterback Drew Brees also rushed for a touchdown as Buffalo slumped to their heaviest home defeat since 2007.