The final round of auditions saw ITV’s talent competition pull in an average audience of 8.4 million viewers.
While the instalment matched the ratings for the equivalent episode last year, it was down on last week's figure of 9.1 million.
The FA Cup Final averaged 7.9 million viewers as fans tuned in to see Arsenal play Chelsea on BBC One.
Doctor Who went head-to-head with Britain's Got Talent, drawing an average of four million viewers, down 200,000 viewers week-on-week.
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Watch as Moffat's writing and Capaldi's acting are yet again blamed for lower than normal viewership despite the BBC not caring one bit about the show's scheduling
Doctor Who viewer
It came as the BBC left viewers of the hit sci-fi programme waiting after The FA Cup coverage overran by six long minutes.
Already moved from its usual slot of 7.20pm, Whovians hit out at the broadcaster, taking to social media to scold putting the eagerly anticipated episode on hold even further.
One person posted: “Hey, @GaryLineker you're great and I'm glad everyone enjoyed the football, but we want #DoctorWho to start now please.”
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Doctor Who series 10: A Complete episode guide for Peter Capaldi's last series as The Doctor.
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A second wrote: “Oh come on football just fast forward the credits already I want #DoctorWho,” as another huffed: “I wish the football would hurry up and f**k off I want to watch #DoctorWho.”
A fourth fan raged: “When the FA Cup overruns so #DoctorWho starts late… @BBCOne needs to get it's priorities in order obviously!”