Duncan Mackenzie used to tell an anecdote about the time he played for Leeds against Liverpool. He was partnering Allan Clarke and they were up against Tommy Smith and Emlyn Hughes. It was well known that Smith hated Clarke and had made it known before the game that he was out for retribution for some incident the previous time they'd played against each other. But the way they were set up meant that Smith was marking Mackenzie, Hughes marking Clarke. Smith spent the first 20 mins of the game snarling at Clarke, telling him what he planned to do should Clarke come within range of him. Then Clarke and Hughes went up for a header, Clarke caught Hughes full on in in the face breaking his nose and a few teeth, blood everywhere. Whilst the game was stopped for Hughes to be patched up, Smith wandered over to Mackenzie, a huge grin on his face, "He's not such a bad lad that Clarkie".
It turned out that the only player Smith hated more than Clark was Emlyn Hughes. This was an ongoing intense dislike, not just a flair up during the heat of a game after conceding a bad goal. But it didnt stop them from winning plenty of medals together.