Medical drama Holby City featured a subtle reference to Doctor Who last night, as it reunited two stars from the most recent series.
John Barrowman is currently appearing in a guest role as Dr Drew Nicholson-Heath, who has joined the hospital in a temporary role to help with their demanding number of patients.
Of course, Barrowman is arguably best known for playing Captain Jack Harkness in Doctor Who and its spin-off Torchwood, but he wasn't the only familiar face from the hit sci-fi series.
Jo Martin also stars in Holby City as neurosurgeon Max McGerry, but Whovian's will recognise her as Ruth Clayton - a long lost incarnation of The Doctor, whose true identity was revealed in series 12.
When bringing together these two powerful players from the show, the Holby City team understandably couldn't resist sneaking in a nod to the fan favourite show.
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So, when Max McGerry confronts her new colleague about her suspicions that he's looking to poach her staff, Dr Nicholson Heath refers to her as "Doctor" before giving an enthusiastic salute.
Fans quickly picked up the moment, noting how it echoes the many occasions in Doctor Who where Captain Jack has cheekily saluted his Time Lord ally.
The blink-and-you'll-miss-it moment was later confirmed in a behind-the-scenes video shared by Holby City's official social media profiles, featuring an interview with Barrowman himself.
During a break in shooting, Barrowman and Martin stopped for a chat where he gave her yet another salute, to which she excitedly responded: "I'm melting! My son is gonna die when he sees this!"
Although billed as a one-off appearance, Barrowman hinted that he could return as Dr Nicholson-Heath in future episodes of Holby City.
He added: "It's the first time ever that I've played a character with my Scottish accent - actually I tell a fib there, it's the second time. But this is, rather than just being... well, it could be something more. You never know in the future."
Holby City is available on BBC iPlayer. If you're looking for something else to watch, check out our TV Guide.