At the Junior World Championships in Calgary in 1996 , they finished fifth and a year later in Oberhof third. Since 1999/2000 the duo Oberstolz / Gruber has been among the best in the world. This season, the double ended in eighth place in the overall World Cup standings. Both finished eighth at the 2000 World Championships in Winterberg and fourth at the St. Moritz World Championships in the same year. At the 2002 Winter Olympics in Salt Lake City , they only came 17th. Still, this season was quite successful. In addition to a sixth place in the overall World Cup, the duo won a World Cup for the first time in Lake Placid . The World Championships finished the doubles and in the team in Sigulda 2003 in fifth place. The 2003/04 season both ended in third place. At the 2004 World Championships in Nagano they came in sixth place, in the team they won bronze. At the European Championships in Oberhof in the same year, they even achieved silver in doubles and in the team.
The doubles were particularly successful in the 2004/05 season. They won both the overall World Cup and the overall ranking in the Challenge Cup. The World Championships in Park City, however, they only finished fourth, but they were able to win bronze with the team again. In the following season, Oberstolz / Gruber won the Challenge Cup again and finished second behind the German duo Leitner / Resch . At the 2006 European Championships in Winterberg , the duo won bronze and silver with the team. They finished the 2006 Winter Olympics in their Italian homeland with a personally unsatisfactory fifth place.
The 2006/07 season developed into a duel between Oberstolz / Gruber and Leitner / Resch. The Italians started the season with two wins and won three of the seven races of the season up to the World Championship. At the end of the season they finished second in the World Cup. The world championships in Igls have not been successful for Oberstolz / Gruber based on their demands and the season so far. They only came in fifth. In the 2007/08 season she took second place in the overall World Cup and Challenge Cup. At the European Championships in 2008 in Cesana Pariol , Oberstolz / Gruber won gold and at the World Championships in Oberhof in 2008 they took 21st place. For the second time Gruber and his partner Oberstolz won the overall World Cup 2008/09. At the 2009 World Championships in Lake Placid , they finished fourth.
In the 2009/10 season they achieved one victory, two second and two third places and came third in the overall World Cup. The duo won the Challenge Cup for the third time. They finished fourth at the 2010 Winter Olympics in Vancouver , Canada . In the 2010/11 season he and his partner Oberstolz took second place five times and they came third in the overall World Cup. At the 2011 World Championships in Cesana, they achieved the silver medal. At the World Championships in Sigulda they won the bronze medal.