Amir Khan says he 'couldn't say no' to Terence Crawford fight
Britain's Amir Khan says he "couldn't say no" to a fight against undefeated WBO welterweight world champion Terence Crawford, but insists he still wants to face Kell Brook.
Khan, 32, returned to boxing last April after 23 months away from the sport.
He rejected a payday against Brook to fight 31-year-old American Crawford on 20 April in the United States.
"Winning this fight, people will remember me as a great champion," said Khan.
The former unified light-welterweight world champion told BBC Sport: "I kept thinking the Brook fight would be the next one until I got a phone call from [promoter] Bob Arum saying 'would you want to fight Crawford?'
"Looking at the way he fights and what he has achieved, I couldn't say no to it. It is a massive fight."
Khan lost to Saul Alvarez when he stepped up to middleweight in 2016, but beat Phil lo Greco and Samuel Vargas in his comeback fights last year.
He was criticised by some for his September points win over Vargas, when he was knocked down before recovering to take his record to 33 wins and four defeats.
"I needed a fight to motivate me to work hard and train hard," said Khan.
"Against Vargas and Lo Grego it was hard to motivate myself. This fight against Crawford will motivate me and make me work hard. Outside of Alvarez, this is the biggest test.
"Normally every fight I go into, I am the favourite. This is a fight at my own division where I am not the favourite, which takes a lot off pressure of me and means I will work harder to prove a point. This is a fight I can win."
In December, 32-year-old IBF champion Brook said fellow Briton Khan had "let the public down" and blamed him for a fight between the pair not taking place.
Khan said: "The decision as to fighting Brook or Crawford has been one of the most difficult decisions of my career to date.
"Clearly, the UK fans want to see Khan v Brook, but I could not turn down the opportunity to fight for the WBO title.
"That is not to say that the Brook fight won't happen, as I want that fight to happen as soon as possible."
'Boxing has turned my life around'
Crawford has held world titles at lightweight, super-lightweight and welterweight.
He moved up to the 147lb welterweight class to take his current title from Australia's Jeff Horn in June, and his most recent stoppage win over Jose Benavidez Jr in October took his record to 25 knockouts from 34 wins.
The southpaw says boxing "saved" him, having been shot in the head in 2008.
"Boxing took me off streets at seven years old," Crawford said.
"I was a little bad kid getting into a lot of trouble. I would say boxing saved me because at one point in time I was hanging out with the wrong crowd, getting into a lot of trouble and doing a lot of crazy stuff which could have led to jail.
"I decided to take my career to the next level, give 110% focus on becoming champion of the world. Boxing has turned my life around."
Speaking about being shot in the head while "shooting dice", Crawford said a car window and the distance of the shooter saved his life and that the incident was a "wake-up call".