It ensured a golden sunset on the competition where SA had claimed no fewer than five gold medals with some events still to be completed later on Sunday.
On Saturday Breyton Poole took high jump gold while Sokwakhana Zazini and Zeney van der Walt won the boys’ and girls’ 400m hurdles.
Zazini won by nearly three seconds over his nearest rival‚ while Van der Walt put everything into her finish to edge Jamaican Sanique Walker by four-hundredths of a second after her rival‚ with a handsome lead‚ had stumbled over the final hurdle.
Lemao had taken SA’s first gold on Wednesday in the 100m‚ with Mlenga second.
On Sunday afternoon Mlenga was in front coming out of the turn and he held his advantage all the way to the line to cross in a 21.03sec season’s best.
Lemao was second in a 21.12 personal best and Luis Brandner of Germany third in 21.23‚ also a personal best.
That gold stretched SA’s lead atop the medals table‚ giving them five gold‚ three silver and two bronze‚ ahead of Cuba and China both with four golds.
This will be the final edition of the world under-18 showpiece which started only in 1999.