The forward has received criticism from the Spanish media, who have questioned whether he has the mentality to succeed at Barca, but he responded with a brilliant display against Malaga after Messi missed the trip to attend the birth of his son.
Dembele used a quick cut back in the area to open a passing lane and slipped a ball to Coutinho, who completed the move with a skilful flick of the inside of his right boot to beat Malaga goalkeeper Roberto Jimenez.
Coutinho, relishing a free creative role with no Messi in the side, was close to his second of the night when some smart interchanges saw Paulinho lay-off to his compatriot but Roberto was equal to yet another dangerous effort.
Karim Benzema came on with 20 minutes left, Madrid trying to force a winner, but it was Eibar who went closest when Inui headed over from six yards, while Paulo Oliveira shot straight at Navas.
"He has that ability", Valverde said of Dembele.
"He knows he's going to score, he's unique and special".
- Barcelona are unbeaten in their last 35 LaLiga games (W29 D6) - they need three more to equal the longest unbeaten run of any team in LaLiga history (Real Sociedad, 38 in 1980).
Barcelona are first in the La Liga table with 72 points from 28 matches ahead of Atletico Madrid, who are in the second place with 61 points from 27 matches.
The prolific Portuguese scored for the seventh successive game in all competitions by blasting into the net in the 34th minute after chesting down a long ball by Luka Modric. Fortunately for Barca, whose second-half performance left a bit to be desired, Malaga were wasteful in front of goal.
"For me he's from another galaxy", Madrid manager Zidane said. The Argentina forward later announced his wife gave birth to a boy named Ciro.
"I won't rule [Madrid] out and they will do well not to rule themselves out, too".
"We're trained to have the mentality of game by game at this club".
After again falling short in the Champions League, Paris Saint-Germain got back into the routine of dominating the French league by crushing last-place Metz 5-0 Saturday.
Sevilla trailed Valencia by eight points before kick-off but that gap was stretched to 11 after two goals from Rodrigo Moreno sealed a comfortable victory.
It is a point below Spal and Sassuolo, which occupies the last positions of safety and play each other, also Sunday.