Chelsea face an uphill struggle to reach the Champions League last eight but Willian is confident they can pull off a shock win in Barcelona next month.
Willian came close to upstaging Argentina superstar Lionel Messi in Tuesday night's first leg, firing the Blues into the lead having previously twice been denied by a post.
However, Messi had the final word when he capitalised on a rare Chelsea defensive error to bag his first goal against the west Londoners at the ninth attempt and secure a 1-1 draw.
Nevertheless, Willian saw enough in Chelsea's performance at Stamford Bridge to suggest they can upset the odds in the second leg.