Mo Farah is hailed as Britain's greatest ever athlete after repeating his Olympic success with a double victory at the World Championships.
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Former Olympic sprinter Roger Black was on the edge of his seat as he watched Mo Farah competing in the Men's 5,000m final at the IAAF World Championships:
British Athletics said Mo Farah's second gold at the IAAF World Championships in Moscow "really cements his place in the history books."
The body also urged people to retweet one of its messages if they think Farah "is the greatest British athlete of all time":
Olympic champion Mo Farah showed off his second gold medal after winning the Men's 5,000m finals at the IAAF World Championships in Moscow.
Paralympic champion David Weir as well as Olympians Lutalo Muhammad and Jo Pavey have tweeted their support to Mo Farah, after he became the second man in history to hold the 5,000 and 10,000 Olympic and World Championship titles.
Well done to @mo_farah what a race
Congratulations @mo_farah! absolutely brilliant!
Fantastic @mo_farah Simply awesome mate! So proud of you. xxx
Mo Farah said that it was "hard work" winning today's 5,000 metre final at the World Championships, adding that it was "harder than the last".
He told the BBC:
I never thought in my career I would achieve something like this. This is something I've worked so hard for. All I was thinking about was my kids and how much I've been away from them.
It was hard. It was a lot more hard work than the last, I put so much hard work into it.
Former Olympic sprinter Roger Black has told ITV News that the UK is "witnessing the greatest British athlete we have ever seen", after Mo Farah won his second gold medal at the World Championships today.
Mo Farah's wife Tania says she is "overwhelmed" after he won a historic second gold in the 5,000m at the Moscow World Athletics Championships.
She said watching the race was more nerve-wracking than watching the Olympics, because of the level of expectation. She spoke to reporter Rags Martel.
Manchester United footballer Michael Carrick and former Olympic hurdler Colin Jackson have called Olympic champion Mo Farah's win at the 5,000 metre finals in the World Championships a "class performance".
Another class performance by @mo_farah.... Awesome ?????
British athlete Jessica Ennis-Hill and sports commentator Clare Balding are among the sporting community who have taken to Twitter to congratulate Mo Farah, after he won the 5,000 metre finals at the World Championships.
Never in doubt! Another amazing performance! Go @mo_farah
Unbelievable! Mo Farah is just immense.