Seven teams can progress to the last 16 with two matches to spare after a series of open displays showed that cagey wins and strategic draws are out of vogue in the group stages of the world's elite club competition.
Inter beat Tottenham Hotspur 4-3 at home in a remarkable Group A game last time, and if the holders beat the English club on Tuesday they will go through irrespective of Werder Bremen's result against Twente Enschede.
Rafael Benitez's team was 4-0 up in 35 minutes two weeks ago before Gareth Bale's hat-trick for Spurs. And although the Inter coach will want his injury-hit side to tighten up defensively at White Hart Lane, there is a sense that attack is now the best form of defence.
The Portuguese could be planning an attacking return to the San Siro on Wednesday given that Real know a fourth successive Group G win would put them through to February's first knockout round.
The form of Cristiano Ronaldo, who scored two more goals in Saturday's 3-1 win at Hercules, is a reason for optimism for the nine-times winners - as well as Milan's 2-1 home defeat by Juventus in Serie A this weekend.
"I'm in great form and having a phenomenal run," Ronaldo told reporters.
Two goals sealed Barca's home win over FC Copenhagen in their last Group D game, and the Argentine was prominent again on Saturday with another brace in the 5-0 humbling of Sevilla.
A victory in the Danish capital on Tuesday will herald Barca's progression from the group stage, and a possible rest for Messi in the last two group matches.
Last season's runners-up, Bayern Munich, were lax in defence during the 3-2 win over CFR Cluj a fortnight ago, continuing the overall theme this term, but that result means a top-two finish in Group E could be assured with a point in Wednesday's return.
Arsenal, Chelsea and Olympique Lyon also have nine points from a possible nine, with Arsene Wenger's side topping the scoring so far with a whopping 14 goals. Progression awaits this week for all three if they win, while a draw may suffice for the French club.
"We have matured," Wenger said, adding that Cesc Fabregas is a slight doubt for Wednesday's Group H game at Shakhtar Donetsk.
"You can see that when it doesn't work for us, the players remain calmer than before."
