10. Andy Cole & Teddy Sheringham
Like many sporting rivalries, the feud between former Manchester United and England strikers Teddy Sheringham and Andy Cole started with a single petty act. In early 1995, Cole was about to make his international debut as a 71st-minute substitute in a game between England and Uruguay. Sheringham was the man he'd replace, and the interaction didn't go as Cole had expected.
A bag of nerves as he stepped out onto the Wembley turf, Cole reached for a handshake from Sheringham, but was snubbed. Teddy didn't even make eye contact as he wandered off the pitch, and while this incident seems minor, it sparked 15 years of resentment between the duo.
"From that moment on, I knew Sheringham was not for me," Cole told The Independent in 2010. The duo continued in the international setup together, and Sheringham joined Man United from Tottenham two years later. They won multiple Premier Leagues, the FA Cup, and Champions League together, but didn't speak a single word to each other, despite regularly appearing in the same line-up.
A lengthy spat, but one that was clearly handled professionally behind the scenes, as it did nothing to derail one of United's most decorated periods.