Atletico Madrid then played their part in a day of big wins for the teams at the top of the table when Raul Garcia and David Villa scored two goals apiece to help Atletico Madrid retain a strong hold on second spot with a 7-0 win over 10-man Getafe.
Ronaldo struck after three minutes but the game was still in the balance when he limped off early in the second half.
Karim Benzema settled Real's nerves by curling home the second on 61 minutes before Gareth Bale, Isco and Alvaro Morata consigned Almeria to a resounding defeat.
The main concern was the extent of the leg strain for Ronaldo, who has bagged 14 goals in seven games including four for Portugal in their triumphant two-legged World Cup playoff win over Sweden.
"I don't think it is important," Real coach Carlo Ancelotti told a news conference.
"He had a problem with his thigh but I don't think it will be anything as there was no pain. He will be back soon."
Injury-plagued Barca continued to set the pace after first-half penalties by Andres Iniesta and Cesc Fabregas set them up for victory.
Visiting Granada had Manuel Iturra dismissed after 66 minutes before Alexis Sanchez and Pedro completed the rout for the champions, who were missing a string of players including Lionel Messi, Xavi and keeper Victor Valdes.
Barcelona have 40 points from 14 games and a three-point lead over Atletico Madrid, with city rivals Real a further three points adrift after Saturday's action.
QUICK START
Real pressed Almeria in a storming start and it did not take long for them to go in front as Isco sent Ronaldo through with a searching ball from the right.
Almeria set out to defend deeply with five at the back, a system that has brought them success in recent games, but Real's quality in attack proved too much.
The home side were dangerous on the break with Suso curling a shot just round the post while Benzema headed wide at the other end before a fine run from Ronaldo ended with his shot being saved by Esteban Suarez.
Following the restart, Ronaldo went off holding his leg after battling for the ball with Alex Vidal.
The game had turned scrappy but Benzema produced a fine goal and from there Almeria's heads dropped.
Bale robbed Sebastian Dubarbier to get on the scoresheet before Isco and Morata completed the rout.
"It was a good game as we didn't concede," Ancelotti added. "We played well together and we need to continue this way."
Despite the ease of his side's victory Barcelona coach Gerardo Martino was forced to defend his tactics after the match.
"We had the right balance when going forward and we attacked as a group," he said in response to criticism of the team's more direct style.
"Maybe we could have taken more time in our buildup play. We know here that winning is not sufficient and we have a responsibility with the club to perform in a certain way.
"I have a philosophy of football slightly different to you and I think that passing the ball around 20 times can be entertaining but also 10 times can be enjoyable as well."
GIFTED LEAD
Barcelona were forced to field a makeshift back line with full backs Dani Alves and Jordi Alba out and Javier Mascherano on the bench.
The home side were gifted the lead when Fabregas was needlessly bundled over by Pape Diakhate, allowing stand-in skipper Iniesta to calmly place his penalty into the corner.
Granada's Francisco Piti hit a powerful shot from 25 metres that cannoned off the crossbar midway through the first half with Jose Manuel Pinto well beaten.
Five minutes before the break, Iniesta was fouled in the box and this time Fabregas sent the keeper the wrong way to double the advantage.
Pedro missed a good chance after the break but a second yellow card for the battling Iturra left Granada with a mountain to climb.
Barca wrapped up a convincing win with Alexis finishing clinically from a Neymar pass before Pedro slid home the fourth goal with the Granada defence wide open.
Atletico's success this season has been built on solidity but they tore apart a sorry Getafe in the late game through their attacking play, despite leaving a less-than-fully fit leading scorer Diego Costa on the bench.
Kiko and Arda Turan tormented the fullbacks as Getafe were pushed back and Raul Garcia headed the opening goal from a corner midway through the first half.
Luck was also against the visitors as Albert Lopo diverted a Koke effort past his keeper and then shortly before the break, Juan Valera was dismissed for a second yellow card.
In the second half, the traffic remained flowing in one direction with two headed goals from Villa and Raul Garcia.
Costa was introduced for the last half hour and he scored a spectacular overhead kick before Villa and Adrian Lopez wrapped up a night full of goal action.
