A 2-2 draw with Young Boys on Thursday night means that the Reds need to get a win at Udinese in order to guarantee progress in the competition, but Shelvey remains confident.
"We are a bit disappointed we didn't qualify against Young Boys," Shelvey told the official site. "We felt that we should have won the game but it was just a lack of concentration towards the end that cost us.
"We'll push on from here and get the three points against Udinese to make sure we qualify.
"It will be a difficult game against them - it was a difficult game here. But that being said, I thought that day we should have won. So we'll go there with the same game plan and hopefully we will nick a result."