Liverpool looked like it would take a narrow lead into next Wednesday's second leg at Stamford Bridge when Riise, a second-half sub for the injured Fabio Aurelio, ducked down in an attempt to head Salomon Kalou's cross away with Nicolas Anelka lurking at his back, but all Riise could do was knock the ball past keeper Pepe Reina into their own goal.
Liverpool manager Rafael Benitez was unhappy with decision of Austrian referee Konrad Plautz to add five minutes of stoppage time in the second half.
"It was a difficult match and I was very disappointed with the referee," he said. "This was not the first time. We knew what to expect because we'd had him before against Marseille. He gave just one minute of injury-time in the first period and four in the second. It was hard to understand."
Benitez did not like the way Plautz's calls went.
"All the free kicks seemed to go against us," he said. "The first four free kicks against us were for pushing, and then when one of their players [Ashley Cole] pushes one of ours in the back with both hands in the box, there's nothing. But we cannot blame the referee for our missed chances. We had at least four clear opportunities, and we must score those. But we must now be positive and clear our minds. If we play like that at Stamford Bridge next week and take those chances, we will go through."
Chelsea manager Avram Grant said the result was justified.
"We have conceded a lot of late goals this season," he said, "so it was good to see one go in our favor. I felt we deserved it. There could have been a couple of penalties for us and we controlled the game until Liverpool scored. Both goals came from mistakes, but I must also praise [Chelsea goalie] Petr Cech for his performance. He made some important saves, but we are used to that from him. But although the draw is good for us, we know it will be tough at Stamford Bridge. It is always difficult for teams to play at Anfield with the support Liverpool's fans create, but it can also be intimidating for teams who visit Stamford Bridge."
April 22 in Liverpool
Liverpool 1 Chelsea 1. Goals: Kuyt 43; own goal 95+.
Liverpool -- Reina, Alvaro Arbeloa, Carragher, Skrtel, Fabio Aurelio (Riise, 62), Xabi Alonso, Mascherano, Gerrard, Kuyt, Babel (Benayoun, 76), Fernando Torres.
Chelsea -- Cech, Paulo Ferreira, Terry, Ricardo Carvalho, A.Cole, Lampard, Makelele, Ballack (Anelka 86), Malouda, Drogba, J.Cole (Kalou, 63).
Referee: Konrad Plautz (Austria).