The pair were firm friends during the late 90s and early 00s, and were both reported in the running to replace Chris Evans on the station before it was announced Zoe had landed the job last year.
After beating Sara to the role, Zoe has now spoken out to insist they have been supportive of each other, despite no longer being as close as they once were.
Zoe told the Radio Times that Sara had even beaten her to jobs she had wanted in the past.
She said: “We spoke a lot during the whole process. We’re old buddies and we’ve always been really supportive of each other.
“Sometimes she gets jobs I’ve wanted. We always talk. It worked out.”
Zoe, who starts on the Breakfast Show on Monday, explained they “don’t see each other a huge amount any more”, but added: “Professionally, work-wise, we’ve always supported each other.”
Despite losing out on the breakfast slot, Sara will be also starting a new role next week, as she takes over from Simon Mayo and Jo Whiley as the host of the Radio 2 drivetime show.
“We start on the same day, which is wonderful,” Zoe said. “We are going to ring each other before to try to keep calm. She’s an amazing broadcaster. She cracks me up. She has so much energy.”
She added: “It’s all turned out rather nice.”
Both presenters previously hosted the Radio 1 Breakfast Show – Zoe from 1998 until 2000 and Sara from 2000 until 2003 – but Zoe has insisted their lifestyles will be very different as they take up their new gigs.
Zoe said: “We were reminiscing about the first time round, when sometimes we didn’t sleep at all. It’s so different now. We need eight hours or we’re really grumpy. Or seven with an afternoon nap.”
The full interview appears in the new issue of the Radio Times, on sale now.