Douvan's winning run came to a shuddering halt as Special Tiara claimed victory in the Betway Queen Mother Champion Chase, the feature race on day two of the Cheltenham Festival.All eyes were on the Willie Mullins-trained Douvan, the brilliant seven-year-old who had won 14 races on the spin and was sent off the 2-9 favourite.But after jumping a little too exuberantly in places, he looked in serious trouble two fences from home - and so it proved.Whereas Douvan retreated, eventually finishing down the field, the front-running Special Tiara (11-1) kept up an honest gallop under Noel Fehily and gamely fended off Fox Norton by a head.Fehily, who won the Champion Hurdle on Tuesday, said: "Unbelievable. He's such a great ride, he's everything a two-mile chaser should be. He's a very good horse."I didn't think so (beat Douvan), but I thought I had a great chance of being second. I got over the last and was surprised something hadn't come to me, but I knew he wasn't stopping."He has one way of running and that's flat to the mat and jump - I just let him get on with it."I've always loved two-mile chasers, the Champion Chase is the one you want to win. To win it is fantastic."Winning trainer Henry de Bromhead said: "It's an amazing day, I'm just so pleased for everyone involved."He seemed in great form coming into it, but it was hard to believe (could win) with Douvan and everything else - Douvan had looked so good."For our lad, he just tries his heart out and no-one deserves it more."I thought he jumped the slickest he's ever jumped. Often he jumps a bit high. Incredible."Any day you win a Grade One at Cheltenham is just an amazing day."