Tana Umaga has failed to get past the Chiefs' first training run in South Africa and is on his way to New Zealand again.

The veteran former All Blacks skipper pulled a calf muscle in the light session in Johannesburg on Monday, having missed the previous Super Rugby match against the Crusaders last Friday night.

Umaga has been replaced by fellow midfield back Jackson Willison, who arrived in South Africa to join the squad in Johannesburg early this morning.

The Chiefs will take on the Lions on Sunday at 5.10am.

Story by: Dreu Vukailagi