Police appeal for information to help find the two suspects.
Two men had been picked up by a taxi at around 12.30am from the taxi rank near Yates pub in Swansea city centre and asked to be taken to Birchgrove and Tonna.
While the taxi was stopped at Heol Nant Bran in Birchgrove an altercation took place which resulted in the driver being assaulted and the men running off.
The suspects are described as being aged in their 30s and were wearing work clothes, including dirty jeans, light coloured t-shirts and working boots. It is believed they had been drinking in the city centre on Saturday night.
Anyone with information about the incident or anyone who knows the identity of the suspects from the description should contact police on 101 or Crimestoppers anonymously on 0800 555 111 quoting occurrence number 1600096630.