Former Tottenham goalkeeper Pat Jennings was taken to hospital after collapsing before the clash with Chelsea on Monday night.
Jennings, 78, was at the Tottenham Hotspur Stadium for the London derby, with Chelsea emerging as 4-1 winners after a frantic encounter that saw two Spurs players dismissed.
Jennings fell ill and collapsed before kick-off and was taken to a local hospital after being treated by medics. He underwent tests at hospital and when they came back all clear, he was released shortly before midnight.
Jennings, who won over 100 caps for Northern Ireland, spent 13 years with Spurs and made almost 600 appearances, winning the FA Cup, two League Cups and UEFA Cup before joining rivals Arsenal in 1985.
He returned to Tottenham for a brief stint before becoming goalkeeping coach in 1993, working alongside the likes of Ian Walker and Paul Robinson. He has continued working with the club's academy sides well into his 70s.
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He admitted earlier this year that leaving his former club was 'the worst day of my life' but insisted there was no doubt which side of north London he favours.
Jennings said: “I have been, 43 years, at Tottenham now, within the coaching staff and as a player. Forty-three years. There is no doubt where my loyalties lie. But, having said that, I have never had a bad word to say about Arsenal.”
The clash on Monday night saw two red cards, five goals scored and five more disallowed in a frantic encounter. Spurs ended the match with nine men after Cristian Romero and Destiny Udogie were dismissed.
Chelsea had struggled to break down the resolute hosts but made their advantage count in the closing stages as Nicolas Jackson capitalised to score a hat-trick.
Spurs were also dealt a double injury blow with James Maddison and Micky van de Ven forced off, meaning they finished with just four outfield players who started the match.
The defeat is Tottenham's first in the Premier League under Ange Postecoglou and they remain second in the table, one point behind Manchester City.