Brian Dietzen left his fans momentarily taken aback with a recent photograph he shared on social media featuring his co-star Katrina Law.
MORE: NCIS' Brian Dietzen gives rare insight into his family life away from the spotlight
The picture saw the two of them looking exhausted but happy, although their clothes were stained with sweat and blood.
VIDEO: NCIS and NCIS: Hawaii tease major crossover
While initially believing it to be a teaser for something to come, Brian made it clear in his caption that it was in fact a tribute.
The picture was a sweet birthday shout-out to his co-star, referencing the long and grueling days they spend on set filming NCIS.
MORE: NCIS' Brian Dietzen teases stirring plot point ahead of new episode
"Happy birthday to one of the absolute best people to spend long days on set with. Have a great one, @katrinalaw!" he wrote.
The official CBS Twitter account left a comment that read: "HAPPY BIRTHDAY TO THE QUEEN @katrinalaw! We are so happy to have you be a part of the CBS Family."
Brian paid a birthday tribute to his co-star Katrina
"I love these two together. About time they had some good times & fun & happiness amongst all the bloodshed & trouble," a fan said, with another jokingly adding: "And all you got her for her Birthday is blood stained clothes! C'mon man… STEP UP!"
While Brian's Dr. Jimmy Palmer has been a staple on the series since season one, he eventually became a regular character in season ten, having become a major fan favorite too.
MORE: Pauley Perrette looks unrecognisable with long blond hair transformation in epic throwback
MORE: Michael Weatherly's special romantic gesture to wife Bojana Jankovic is so touching
Katrina, on the other hand, first made guest appearances in season 18 and was eventually promoted to main character status the following season.
The two characters started off as best friends, but eventually, sparks began to fly as they admitted their feelings for one another in the season 19 finale.
© Photo: Getty ImagesThe two have been praised for their on-screen chemistry
In an interview with Entertainment Tonight previously, Brian spoke of his experience working with Katrina, saying: "Ever since Katrina joined the show, we've really enjoyed having scenes together.
"Whether it's the evidence findings [or] coming down to autopsy. We've always found some way to enjoy the scene. And they've given us some great scenes together too."
Read more HELLO! US stories here
Like this story? Sign up to our newsletter to get other stories like this delivered straight to your inbox.
