Cristiano Ronaldo scored his 100th Real Madrid goal as they beat Lyon 2-0 at the Stade Gerland in Champions League Group D.

The result means that Real, with four wins from four so far, are guaranteed a place in the last 16 of the competition.

Ronaldo, who brought up his personal landmark in just his 105th match for the club, scored both goals, backing up a first-half free-kick with a second-half penalty.

After Ajax eased to a 4-0 victory over Dinamo Zagreb in the other Group D game, Lyon now face an uphill task to reach the last 16 themselves for a ninth successive time.

Despite having spent handsomely over recent seasons on one of Europe's strongest squads, injuries forced Jose Mourinho to deploy midfielder Lassana Diarra in the unfamiliar right-back position. Lyon too were shorn of several key players, with Michel Bastos, Lisandro Lopez and Aly Cissokho all missing, and emergency goalkeeper Mathieu Valverde, only signed this week on a short-term deal contract, named on the bench.

Real Madrid, who have won their last two games against the French side, started the better, with Ronaldo firing an early warning shot from distance which Hugo Lloris saved.

The visitors seemed able to get behind the Lyon defence with impunity - Ronaldo and Angel Di Maria were consistently picked out with some superb passes from deep, with Xabi Alonso particularly effective.

Lyon old boy Karim Benzema should have been the one to break the deadlock, left in acres of space but his placed shot at the near post was tipped around the upright by the busy Lloris.

The hosts struggled to keep the Spanish side out of their half, and the opening goal looked inevitable.

In the end it was Ronaldo who scored it, thundering a free-kick from the D of the penalty area low into the corner.

The only surprise by the interval was that Madrid had not doubled their advantage.

They had no shortage of chances. Di Maria saw his shot blocked by a despairing dive from Dejan Lovren after half an hour, and two minutes later Benzema hit Ronaldo's low cross straight at Lloris as the Lyon defence sleepwalked.

Mesut Ozil blew a chance of his own with a tame finish after spectacular counter-attacking from Benzema and Di Maria.

And against the run of play, Lyon had a chance to reach the break on level terms, with the often isolated Bafetimbi Gomis picking out Yoann Gourcuff - he lashed in his shot at a saveable height, and Iker Casillas was able to tip it over the crossbar.

Lyon opened up a little in the second half, improving on a limp opening 45 minutes. But their extra adventure up front left them vulnerable at the back.

Cris had to judge his sliding tackle to perfection to deny Di Maria in the penalty area just after the hour, while Lloris needed to be on his guard to deny Ronaldo with a deceptive shot creeping in at the near post.

Lyon had their chances, the best of which fell to Ederson, who on 68 minutes did so well to fashion space for a shot in the area, only to then fire straight at Casillas.

And that missed opportunity was punished immediately as the visitors surged down to the other end of the pitch.

The ball landed at Ronaldo's feet as Ozil ran into the box and towards Lloris, and as the Portuguese tried to keep possession he was brought down by Mouhamadou Dabo.

He drilled the penalty straight down the middle for his 100th goal since his move from Manchester United little more than two years ago.

The game was up, but the chances kept flowing.

Di Maria drew another save from Lloris before at the other end Jimmy Briand headed a Gourcuff corner against the woodwork.

But there was to be no third goal, and Real Madrid continued their serene progress towards the last 16, reaching the knockout phases with two games to spare.

Mark Patterson - on Twitter @markjpatterson / Eurosport