Tensions threatened to reach a fever pitch between Washington Nationals outfielder Bryce Harper and home plate umpire Laz Diaz during Friday night's game in Atlanta.

It started when Harper took issue with Diaz's strike zone during an at-bat in the fifth inning. It continued with the Nationals on defense as Diaz argued with manager Dave Martinez about Harper appearing to further criticize the strike zone from his place in the outfield.

(Video courtesy: MLB.com)

A bad strike call in the top of the seventh almost led to another heated confrontation, but Martinez intervened. After the game, he was not pleased with how Diaz handled the situation.

"I'm not going to make any comments on balls and strikes there, but umpires are supposed to be nonconfrontational, they're supposed to uphold the peace on the baseball field," Martinez said, according to ESPN. "For me, I think the MLB needs to take a look at that. That's all I'm going to say. I've known Laz for a very long time and I'm not going to throw anybody under the bus, but we're in a pivotal moment of the game and he's saying things to Harp and I thought that was uncalled for."

Neither Martinez nor Harper were ejected, and cooler heads ultimately prevailed.