Riis joined Bristol City from Preston this summer
Emil Riis scored twice as Bristol City moved into the Championship play-off places with a 4-2 win over Hull City at Ashton Gate.
Joe Gelhardt put Hull in front early on before Riis levelled with his first goal for the Robins and Gerhard Struber's side never looked back.
Anis Mehmeti completed the turnaround before Riis scored again before the break.
Max Bird sealed the points for the hosts, firing home from close range, before Kyle Joseph netted a consolation in stoppage time.
Hull took the lead inside three minutes. After winning the ball high, the Tigers swarmed forward before Gelhardt expertly dinked it over Radek Vitek.
The hosts attempted to hit back quickly, and were rewarded when Riis levelled 15 minutes later. Zak Vyner's cross was prodded goalwards by Ross McCrorie, leaving the Dane to poke home.
They didn't need to wait long for the lead. McCrorie was involved again just after the half-hour mark, this time nodding Scott Twine's cross into Mehmeti's path, and he finished from close range.
Riis grabbed his second just before half-time, slotting home after dispossessing a Hull defender to put Bristol City in full control.
The second half didn't bring much respite for Hull as Riis went searching for his hat-trick. He went close with a chip over the goalkeeper, but it clipped the bar.
Vitek made a superb save from Ollie McBurnie's header at one end, before Bristol City then hit the woodwork again at the other, this time through Mehmeti.
Bristol City looked like scoring with every attack and Bird got in on the act, emphatically converting Mehmeti's cross.
Joseph gave the travelling Hull fans something to cheer when he finished from David Akinola's cross but it was too little, too late.
'This is the football I love' - reaction
Bristol City manager Gerhard Struber speaking to BBC Radio Bristol: "It was a really good atmosphere, the mood was good and I really liked the reaction to the goal we conceded.
"The character and mentality was great; this was the football I love, very diagonal and stressful [for Hull].
"In the second half, we needed Radek [Vitek], he did a great job. In the end, we deserved the win and I was really happy with how we dealt with challenging moments.
"The team was really good; how we reacted to the goal we conceded was the biggest impression from us."
Struber: "This was exactly the football that I love"
Hull City manager Sergei Jakirovic speaking to BBC Radio Humberside: "I think we entered well in the game and scored but we had a lot of problems on the ball. Every mistake, they punished us.
"We were better in the second half. For 30 minutes we were good. We had three or four good chances, like the Oli McBurnie header but Vitek made a good save.
"We have problems in defence. We have to be better. We didn't stick to our tactical plan or football principles that we train with every day. That is why we lost the game.
"I don't have a problem losing the game, I have a problem when you go away from your principles. That is a bigger problem.
"In my opinion if we got to 3-2 it is a different game. This is football, their goalkeeper was great today.
"We have conceded 12 goals in four games. It is a lot and we need to improve everything in defence."
Jakirovic on Tigers' loss
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