Juan Smith says last Saturday's Test against Argentina in Salta was 'the darkest day' of his rugby career.

The blindside flanker made his first appearance for the Springboks since November 2010 and was substituted in the 52nd minute. 

'What should have been my finest moment in a Bok jersey turned out to be the darkest day of my rugby career,' Smith told Volksblad.

Smith also explained why he didn't sing the national anthem before the game.

'The build-up to the Test was very emotional. During the anthem I had to bite my lips to stop the tears from flowing. It's disappointing that people think I have no respect for our national anthem after [playing] 70 Tests.'

Smith was left out of the Bok squad to tour Australasia but has been placed on standby in case Willem Alberts is not fit to depart on Saturday.

Photo: Gabriel Rossi/Getty Images