If you turned your television set off or rolled over and went to sleep early thinking the Oklahoma City Thunder had Monday night’s game in hand, then you missed a textbook comeback by the Dallas Mavericks.

The Mavs had trailed by 15 points in the final five minutes and it seemed like the Thunder had avoided putting themselves in a win-or-go-home situation. But that is exactly where they are now after Dirk Nowitzki put on another unbelievable display in leading the Mavs to a 112-105 overtime win and a 3-1 edge in this Western Conference finals series.

Did I mention the series is now headed back to Dallas for a closeout Game 5?

It will be hard for the Thunder to shake their colossal collapse in the waning minutes of regulation on Monday night. Oklahoma City stars Kevin Durant and Russell Westbrook missed all kinds of shots down the stretch. In the meantime, unstoppable Nowitzki was money.

The Mavs star scored 12 points in the final 4:43 of regulation, going 4-for-4 from the field while also hitting two clutch-free three throws in the final six seconds to force the extra period. Nowitzki finished with 40 points.

But bigger than the points was the way in which Nowitzki led his team, while Durant and Westbrook simply fell apart after such a forceful start. The Mavs never led in the game until 16 minutes in overtime when Nowitzki knocked down two free throws. There seemed to be little doubt which team deserved to win after such an improbable comeback.

Now if there was any doubt who will represent the West in NBA finals, it’s erased now.

"There's times and situations where they are going to test the courage and the mental inner strength of your team," said Dallas guard Jason Terry, who had 20 points. "This was one of those times.

"This was a defining moment in our season where we look back and say, 'Hey, that was the game.' "

It will also be defining for the Thunder for other reasons. Clearly, this team isn’t quite as ready as it appeared a season ago. Durant and Westbrook need seasoning and the Thunder needs someone who can defend Nowitzki if they have any hopes of getting past Dallas next year.

"There's no doubt it was a tough loss," Thunder coach Scott Brooks said to the media Monday night. "If this loss did not hurt, there's no such thing as a loss that can hurt you."

Contact Terrance Harris at terrancefharris@gmail.com or follow him on Twitter @Terranceharris

(Photo: AP Photo/Sue Ogrocki)