An extra five minutes became necessary to determine a victor after Chicago captain Jonathan Toews tied the game on a power play with 38.5 seconds remaining in the third period.
In overtime, Knuble parked himself in front of Corey Crawford, took a pass from Marcus Johansson and dragged the puck to his forehand before flipping it over the goaltender’s glove. Johansson atoned for committing the hooking penalty that led to Toews’ marker.
Washington moved within one point of idle Philadelphia for the Eastern Conference’s best record.
Nick Leddy and Tomas Kopecky also lit the lamp for Chicago, which has lost three in a row after winning eight straight. Crawford stopped 38 shots in defeat.
Laich had given Washington a 3-2 lead at 6:23 of the third, but the Blackhawks were awarded a power play with 1:50 remaining. Chicago then pulled Crawford to create a 6-on-4 advantage.
Duncan Keith let go a one-timer from the right point that sailed wide of the net. The puck, though, bounced off the end boards and came out the other side to Toews at the left post. Toews wasted little time banking the puck off the sprawled netminder.
Leddy opened the scoring 4:46 into the contest, but Washington grabbed a 2-1 lead in the first period on goals from Gordon and Arnott.
A little over a minute after Leddy turned on the red light, Johansson went off for hooking. Unlike his later infraction, it was the Capitals who took advantage as Gordon pumped home a short-handed goal at 6:11. Arnott scored a power-play goal with 54 seconds left.
Chicago pulled even at 3:09 of the second period when Kopecky beat Holtby from a sharp angle.
Washington defenseman Dennis Wideman collected two assists…The Capitals notched their 40th win of the season, marking the first time the franchise has recorded as many wins in four straight seasons.. The previous mark was three, from 1983-84 through 1985-86…Washington improved to 22-16-4 when allowing the first goal.
On Friday, the Blackhawks were welcomed to the White House by President Obama, who honored them for their 2009-10 Stanley Cup championship.
Today, they have more business in Washington -- taking care, we hope, of the Capitals in the only regular-season meeting between the two teams this season. In fact, they last met one day short of one year ago, on March 14, 2010 at the United Center. On that day, Caps star Alex Ovechkin boarded the Hawks' Brian Campbell, injuring Campbell. Ovechkin was ejected and suspended for two games as a result, and Campbell didn't return until the playoffs.
The Caps won 14 in a row earlier this year to get to the top of the Eastern Conference standings, and have now won seven straight. The Blackhawks had a nine-game winning streak snapped this week and have come off two tough losses in Florida, to the Panthers and Lightning.
It's a key game for the Blackhawks, who are one point out of fourth place in the West and seven points off the Central Division lead behind the Red Wings.
The game is on national TV on NBC at 11:30 a.m. CDT -- Daylight Saving Time begins today, if you haven't already turned your clocks forward, make sure you do it so you don't miss this game.