Wales had flanker Dean Thomas was sent off as they fell to their fourth successive poor defeat in South Africa. Thomas, who had arrived as a tour replacement 36 hours before kick-off, was dismissed in the 62nd minute of his Welsh debut for a straight-arm tackle on Len van Riet.
As the 22-year-old Swansea forward left the field at Van der Bijlpark, a bottle thrown from the crowd narrowly missed him.
Wales were trailing 27-20 when Thomas received his marching orders. Van Riet cut inside off his wing and was poleaxed as Thomas attempted a despairing cover tackle. South African referee Carl Spannenberg had no hesitation in issuing the red card.
Wales responded with a brave fight back in the final quarter which took them closest to a victory in their four matches in the Republic.
A slow start again let them down. The Welsh conceded two straight-forward tries early in the match, by Werner Geyer and Dewet Strydom.
The tourists were eventually outscored by six tries to four after a free-flowing second half, but coach Dennis John will take heart from the recovery as he prepares his squad for Saturday's Test against the Springboks.
John Funnell, Paul Arnold, Lenny Woodard, and Mark Taylor all scored their first tries of the tour for Wales, who were also indebted to three penalties and three conversions from Ebbw Vale outside-half Byron Hayward.
Gauteng Falcons: Matthys; Geyer, Lourens, Meyer, van Riet; van Straaten, de Kock; Williamson, van der Walt, le Roux, Schroeder, Boardman, Strydom, Rossouw, Volschenk.
Wales: Williams; Woodard, G Evans, Funnell, Rees; Hayward, John; Morris, Jenkins, B Evans, Arnold, Stephens, Lewis, Thomas, Wyatt.
Referee: C Spannerberg (S Africa).
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