In the sport's first top-level event featuring both sexes, Steffen held off two fast-charging male swimmers to anchor Germany to victory in a 4x50-meter mixed relay at the World Cup meet Tuesday in Dubai.
Steffen, a world record-holder in the 50 freestyle, started the final leg with a lead of half a pool length. Hungary's Krisztian Takacs and Ukraine's Sergii Frolov took off after her and closed the gap, but Steffen made sure Germany won by a comfortable margin.
Germany finished in 1 minute, 43.21 seconds — 2.10 seconds faster than Hungary. Ukraine was a further 0.58 seconds back.
Swimming's governing body says mixed relays could be introduced at the short-course world championships in Istanbul in December.