The Hammers are said to be eager to buy the Colombian, as they look for a new striker.
Defoe has played alongside Morelos at Rangers for over half a year now, and he has even compared the striker to Harry Kane.
"He's got huge potential," Defoe said to Sky Sports. "I knew about him before but you don't realise how good he is till you see him train and you see him in games. The sky's the limit for him. If he played in the Premier League, he would score goals.
"At Tottenham, when we had Harry Kane as a youngster, I remember saying that I believed he should play more and that he would go on to score a lot of goals for the club.
"What he has done is unbelievable. And I think Alfredo's got that. When you're a natural goalscorer, you can score goals at any level in any league.”
West Ham are known to be looking to strengthen their strike force, with Sebastian Haller now set to arrive.
If Morelos was to join West Ham it would be a major blow to Rangers, and Steven Gerrard’s side are unlikely to let him go cheaply.
Morelos scored 30 goals in 48 games for Rangers last season, which has attracted the attentions of a range of clubs.
He is still rather unproven, and his disciplinary record remains a concern, but if West Ham could nurture him into a clinical finisher like Kane then he would be a brilliant addition to their squad.
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