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.
Jason Arnott, Brooks Laich and Boyd Gordon also tallied for the Southeast Division-leading Capitals, who have won five straight at Verizon Center. Braden Holtby, making his third consecutive start, made 27 saves.
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.