TV
Rex Features
Stelling, who presents Soccer Saturday on Sky Sports, will take over from Des O'Connor as host of the Channel 4 quiz in January.
"I am delighted to be hosting Countdown and follow in the footsteps of such great broadcasters as Richard Whitely, Des Lynam and Des O'Connor," the father-of-three told The Sun.
Riley, who replaces Carol Vorderman as co-presenter, beat 1,000 applicants for the post despite having no TV experience.
She said: "This is the best graduate job in the world. There's only one cool maths job around and I was lucky enough to get it so I'm absolutely thrilled."
Helen Warner, head of Channel 4 daytime, commented: "They make a great team and I feel certain that our much-loved words and numbers game will go from strength to strength with them at the helm."
Tube Talk
'Freaks and Geeks': Tube Talk GoldTube Talk Gold heads back to the '80s and remembers Freaks and Geeks.
TV Interviews
'Celebrity Apprentice' Debbie Gibson Q&ADebbie Gibson opens up about her Celebrity Apprentice experience.
Reality Bites
Does Simon Cowell have new SuBo?: VideoWatch a clip of Jonathan Antoine, who is tipped for success on BGT.
TV Ratings
Judi Dench draws 4.1m on 'Graham Norton'ITV1 pips BBC One to the highest primetime audience share.
