The Serie A giants host Dnipro in the competition on Thursday, and know a draw will send them through to the last 32.
Despite their poor start to the league campaign - which saw Walter Mazzarri replaced by Roberto Mancini last week - Inter's continental form has been good.
Two wins and two draws sees Inter sit four points clear at the top of Group F - with the remaining three teams only separated by goal difference.
Mancini's first match in charge ended in a 1-1 derby draw with Milan on Sunday and Juan wants his side to build on the result.
"Thursday's going to be a tough game," he told Inter's official website.
"But we have to win it so that we can put the group stage to bed."
A positive result would allow Inter to primarily focus on domestic matters ahead of matchday six - something that would be useful given the tactical changes Mancini has made.
The former Galatasaray boss has switched to a system of four defenders at the back, as opposed to the three employed by Mazzarri.
Of the recent adjustment, Juan said: "I think we did a pretty job [against Milan].
"We're still not completely used to all the movements we have to make but the boss is helping us and it'll come.
"I need to keep learning and improving myself so that I don't make any mistakes at all."
Inter needed a 61st-minute equaliser from Joel Obi to earn a point against Milan after Jeremy Menez's early strike.
Both sides were denied by the woodwork in the latter stages of an entertaining contest, with Inter sitting ninth in the table as a result - already 14 points behind three-time defending champions Juventus.
Things are much smoother for Dnipro on the domestic front, although a 1-1 home draw against Hoverla on Saturday saw them drop three points behind leaders of the Ukraine top flight, Dynamo Kiev.
Dnipro are still second, however, and will be encouraged by the form of Croatian forward Nikola Kalinic, who has netted six goals in his last seven matches.
The Ukrainians, who took just one point from their first three pool matches, kept their campaign alive with a 2-1 win at Qarabag earlier this month.
It was no surprise that Kalinic scored both in that triumph but he was unable to affect the game as a late substitute in Dnipro's 1-0 home loss to Inter in September.
Danilo D'Ambrosio scored the only goal of that match with just 19 minutes remaining.
