Ahead of Saturday’s league meeting, we’ve picked out nine players who have represented both clubs and take a look at what has happened in their careers since. Scroll down and flick through our picture gallery to see the full list.
1. Aden Flint
The towering centre-back made over 200 appearances for the Robins after signing for the club in 2013. He joined Boro last summer but spent only one season at the Riverside before leaving for Cardiff.
Photo: Catherine Ivill
2. Albert Adomah
One of Boro's promotion winners from the 2015/16 season. The Teessiders signed Adomah from Bristol City in 2013 and the winger, who has since joined Nottingham Forest, remains a popular figure at both clubs.
Photo: Richard Sellers
3. Neil Maddison
The BBC Tees pundit remains heavily involved with Boro's youth set-up in his role as academy ambassador and player welfare manager. During his playing days, Maddison spent four years at Boro and had a brief loan spell at Bristol City.
Photo: Clive Mason
4. Lee Tomlin
After helping Boro reach the Championship play-off final in 2015, Tomlin left Teesside for Bournemouth. He then signed for City permanently following a loan move to Ashton Gate and has since returned to Cardiff after spells at Nottingham Forest and Peterborough.
Photo: Jan Kruger