Barcelona produced a good second-half performance to win 71-57 at Maccabi Tel Aviv on Thursday while CSKA stretched their perfect record this season to 12 wins with Wednesday's 96-68 home rout of Anadolu Efes Istanbul.
With the two teams tied at half-time, 2010 winners Barcelona outscored five-time Euroleague winners Maccabi 42-28 in the second half as Slovenian centre Erazem Lorbek scored nine of his 18 points in the final five minutes.
"Barcelona are a great team and while we matched them for three quarters, we were mentally tired in the final period because we couldn't break them down," Maccabi coach David Blat said.
"Now we have to focus on our next game with (Italian side Benet) Cantu because they will fight with us for the second spot in the group," said Blat, who steered Russia to the 2007 European championship in Spain.
CSKA also made it two wins out of two in the second group stage of the competition, with five of their players ending the match in double scoring digits.
Former Utah Jazz forward Andrei Kirilenko, one of a few players to stay in Europe after the July-December lockout in the NBA ended, led the way for the winners of six Euroleague titles with 15 points and eight rebounds.
"I think it was one of our best games this season as we pointed out to the players how important it is to defend the perimeter and force the opposition to take difficult long-range shots," said CSKA's Lithuanian coach Jonas Kazlauskas.
His counterpart Ufuk Sarica added: "Obviously it's not easy to play here, CSKA has a very good roster and that's why they are unbeaten in the Euroleague this season."
In contrast to Barcelona, their fellow Spaniards and perennial rivals Real Madrid suffered a shock 88-69 defeat by Montepaschi Siena which put the Italians top in their group.
Russian upstarts Unics Kazan matched Siena's achievement with an 89-83 success at holders Panathinaikos Athens thanks to a superb performance by American-born Bosnia forward Henry Domercant, the game's top scorer with 21 points.
The top two teams from each of the four second-stage groups of four will advance to the best-of-five quarter-final series, and the winners of that will qualify for the May 11-13 Final Four in Istanbul.