Namibian teenager Christine Mboma blasted to the seventh fastest time ever run over the women's 400m when she timed 48.54 seconds in Wednesday's track meet in the Polish city of Bydgoszcz. Mboma, who turned 18 last month, improved her own best time, the world junior record, of 49.22sec set in April. The Namibian crushed the field in Bydgoszcz, with Poland's European champion Justyna Swiety-Ersetic coming through the line more than three seconds off the winning pace. The time, the fastest in the world this season, sets Mboma up as a firm favourite for the one-lap race in the July 23-August 8 Tokyo Olympics. Only two athletes still on the circuit have run faster: Olympic champion Shaunae Miller-Uibo of the Bahamas, who is likely to focus on the 200m in Tokyo, and world 400m champion Salwa Eid Naser, although the Bahraini will not be in the Japanese capital after being banned Wednesday for two years over anti-doping discrepancies. rg/lp/bsp