James Allan, 31, shot Craig Burns, 26, and 27-year-old James McSorley with a sawn-off shotgun as they walked in a lane in Hamilton on 27 June.
Mr Burns lost an eye while Mr McSorley had gun pellets lodged in his brain. The attack was blamed on a feud between Allan's friends and Mr McSorley.
Sentence on Allan was deferred and he was remanded in custody.
The High Court in Glasgow heard that the shooting happened at about 14:30.
Mr Burns described hearing a voice before collapsing to the ground after being struck in the face.
Mr McSorley described hearing "a loud bang" then feeling a pain in the back of his head.
The injured men initially fled to a friend's home before Mr Burns was driven to hospital.
He was found to have serious facial injuries and lost an eye.
Police later found Mr McSorley still at the house he had gone to after the shooting.
He was also taken to hospital having suffered wounds to his face, head and shoulder.
It was discovered he had gunshot pellets in his brain "very close" to major blood vessels.
However, doctors decided no surgery was required and he left hospital on 5 July.
Police later recovered a sawn-off shotgun and a balaclava from a bin and DNA tests linked Allan to both items.
The court was told that the attack was apparently sparked by a feud between Allan's friends and Mr McSorley.
It was also claimed that Allan carried out the shooting after jibes were made about someone close to him being sexually assaulted.
Allan is due to be sentenced at the High Court in Edinburgh on 1 February.
A man who carried out a double shooting in South Lanarkshire has pleaded guilty to two charges of attempted murder.