Lionel Messi returned to form with two goals as Barcelona advanced. Fellow Argentina forward Gonzalo Higuain also had a brace for Napoli. And Samuel Eto'o scored for his fourth different team.
On a night of standout individual performances in the Champions League, however, today was a night to forget for Schalke goalkeeper Timo Hildebrand, whose failed clearance led to Eto'o's opening goal in Chelsea's 3-0 win, which put Jose Mourinho's side atop Group E.
Barcelona made it to the last 16 with a 3-1 win over visiting AC Milan, which now has to battle with Ajax and Celtic for second place in Group H.
Atletico Madrid also advanced with a convincing 4-0 victory over Austria Vienna.
Napoli remained level atop Group F with Arsenal following a 3-2 win that eliminated Marseille, while Aaron Ramsey scored the winner as Arsenal won 1-0 at last season's runner-up Borussia Dortmund.
In Barcelona, Messi scored a 30th-minute penalty for his first goal at the Camp Nou Stadium since Sept. 24 before Sergio Busquets doubled the host's lead with an angled header nine minutes later.
An own goal by Barcelona defender Gerard Pique, who latched onto a pass from Kaka just before halftime, made it 2-1, but Messi sealed the win after finishing a combination with Cesc Fabregas in the 83rd.
Barcelona clinched a place in the second round thanks to Ajax's 1-0 victory over Celtic.
Barcelona leads Group H with 10 points, Milan has five points, Ajax has four and Celtic is bottom with three.
Messi has struggled following an injury-riddled October, going four league games without a goal for the first time since the 2010/11 season.
And while the Argentina forward still does not look 100 percent, his finishing touch in front of goal remains unflinching.
In Naples, Higuain's finishing form was also on display. He used one touch for each of his goals, which included a 75th-minute winner following a cross from rapidly developing Belgium forward Dries Mertens.
In London, Eto'o's second came nine minutes into the second half, with Willian slipping the ball through and Eto'o clipping a shot past Hildebrand.
Before going on to score for Barcelona and Inter Milan in the Champions League, Eto'o first netted in Europe's elite competition in Sept. 2001 for Mallorca against Schalke.
After missing out on the knockout phase last season, and dropping into the Europa League, Chelsea just needs one point from the last two Group E games to advance.
Chelsea is three points clear of Schalke, and four clear of Steaua Bucharest, which drew 1-1 at Basel.
In Group G, Atletico got goals from Miranda, Raul Garcia, Filipe Luis and Diego Costa for a club-record fourth straight victory in the Champions League.
Atletico leads with 12 points, Zenit St. Petersburg is next with five after drawing 1-1 with Porto, which has four, while Austria Vienna is last with one.