The One Direction heartthrob - who recently split from his long-term girlfriend Danielle Peazer - has been concerned about his bandmate's welfare since he quit twitter in August over hurtful comments and has pledged to look after him as best he can.
Liam told The Sun newspaper: ''The only person I really worry about is Zayn, because I don't think he's quite accustomed to all of this. He's had a terrible time on twitter, as did Danielle.
''I don't think he's quite adjusted to it yet, I'm sure he'll get it. He's my best mate. I've got to look out for him.
The 'Live While We're Young' hitmakers shot to fame on singing competition 'The X Factor' in 2010 and Liam is grateful the opportunity saved him from ''working in a factory on a normal wage'' making jet parts in Wolverhampton.
The 19-year-old star admitted he came close to giving up on his dream following a disastrous gig in North Wales.
He sighed: ''I played for ten people for £50. That had to be my worst gig - that was the last straw. I was like, 'I'm not doing this any more dad, I don't want to'.''
Although Liam couldn't be happier with One Direction's success, he is realistic about how long their popularity can last and revealed the most important thing about his career is his close friendship with his bandmates.
He said: ''There is going to come a time when it all finishes and I just hope we stay mates.
''It's mad to think I didn't know them two years ago and now they're my best mates.''
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