The Queensland fullback Luke Morahan scored a match-winning try as the Reds fought back from 15 points down to beat the Waikato Chiefs 23-18 in their Super 14 clash in Hamilton.
The injury-ravaged Reds trailed 15-nil inside the first 20 minutes and also had winger Brando Va'aulu sin binned for a dangerous tackle but fought back to beat the heavily-favoured Chiefs, who had won their first three games away from home.
Chiefs wingers Sitiveni Sivivatu and Lelia Masaga and loosehead prop Sona Taumalolo scored tries, though Stephen Donald missed all three conversions, to give their side a 15-nil lead.
The Reds, however, inspired by Wallaby scrumhalf Will Genia, refused to roll over and responded with a try from winger Will Chambers in the 27th minute, which was converted by Cooper.
Cooper cut the gap further with his third successful penalty and Morahan gave his side the lead for the first time when he outsprinted the Chiefs' defenders from 60 metres out to pounce on a speculative downfield kick.
Cooper converted the try and the Reds held on as the two sides bashed away at each other without yielding for the final 10 minutes.