We face the Swiss Champions at St Jakob Park poised at 2-2 after the first leg at the Lane, where FC Basel led 2-0 before goals from Emmanuel Adebayor and Gylfi Sigurdsson hauled us back into the tie.
"They had a period between 20 and 35 minutes that was difficult for us, but we did well to come back for 2-2," said Lewis.
"The positive is that we recovered after going 2-0 down, but it wasn’t up to our standards.
"We wanted to win the game and go into the second leg with a comfortable lead but we’ve now got a tough game in Basel.
"We all believe we have the quality and ability to get the win. The dream is still there.
"It’s not over. There is still a game to play, we’re good away from home, we know we can produce something, the support will be there for us and we have to concentrate and get the win."