LOS ANGELES – Timothy Bradley battered Brandon Rios en route to a ninth-round technical knockout on Saturday in a lopsided welterweight bout that had a dejected Rios announcing his retirement. Bradley retained his World Boxing Organization world title, improving to 33-1-1 with 13 wins inside the distance with the triumph at the Thomas & Mack Center in Las Vegas. Fighting for the first time under the guidance of trainer Teddy Atlas, Bradley was quick and aggressive against a challenger who struggled to make the 147-pound weight limit. Bradley, 32, was fast off the mark, landing a series of combinations in a big first round. Former champ Rios absorbed a big right in the second, but responded in a battling exchange. He was doing good work in the third before a body shot from Bradley clearly rattled him.