The injured thumb of One Direction's Niall Horan has been causing some problems as their headline North American tour continues.

Horan tweeted yesterday (June 3) that he had injured his thumb, and that it was now healing.

The singer even posted a close up photo of the sorry looking digit, looking bloodied and a tad sore.

He later said on Twitter that it has been causing him some problems on stage - hampering his ability to play guitar. He said:

"What a great show in chicago, thank you all soo much, struggled playin guitar with my gomey thumb! But its cool! Xx"

Horan meanwhile tweeted today (June 4) that he band have been enjoying their time in Chicago. He said:

"What a great days golf at medinah in chicago, home of ryder cup 2012, some craic out there! We had a great laugh."