A decision to cut the corner proved a masterstroke for Mark Du Plessis as he guided Rock Diva to victory in the Auckland Cup.

Rock Diva started favourite for the 3200m Group One contest at Ellerslie but jumped badly from her wide draw and settled last in the running.

The experience which had brought Du Plessis two previous Auckland Cups came to the fore as he stayed on the rail coming around the home turn while other horses were going wide.

Rock Diva reeled in King Kamada near the line to win by three-quarters of a length.

"He's managed to save a few lengths and it might have made the difference," Rock Diva's trainer Tony Pike said of Du Plessis.

"He summed it up perfectly."

The Auckland Cup was Rock Diva's first win since the Sunline Vase on the corresponding program last year.

She had been unlucky in a number of races since then but that may have worked to her advantage on Wednesday.

"She probably should have won one of the bigger races by now but it meant she slipped into the cup on 52kg," Pike said.

Du Plessis had won previous Auckland Cups on Bazelle in 2004 and Prize Lady in 2006, both mares and both carrying the same 52kg weight as Rock Diva.

"I only really had one instruction and that was to just get her to relax the first half," he said.

"I didn't think she would be last but we just summed it up as she went round, she was in a beautiful rhythm and I was able to get a bit of luck in the straight."

King Kamada's trainer Lisa Latta was delighted with her horse's run and said he was beaten by a better horse on the day.