Hydrolase that catalyzes the hydrolysis of 2,4-didehydro-3-deoxy-L-rhamnonate to pyruvate and L-lactate. Can also hydrolyze L-2,4-diketo-3-deoxylyxonate and L-2,4-diketo-3-deoxymannonate. In vitro can also use acylpyruvates such as acetylpyruvate and trimethylacetopyruvate. Catalyzes the fifth (last) step in an alternative pathway for rhamnose utilization that does not involve phosphorylated intermediates