Madrid's seventh consecutive league win lifted it three points ahead of defending champion Barcelona, which tied Athletic Bilbao 2-2. Valencia is four points back.
Osasuna played with 10 men from early in the second half and Ronaldo scored two more to record his fourth three-goal game in the league this season before substitute Karim Benzema capped the rout with a late brace.
"My goals are not important, what counts is that the team wins," said Ronaldo, who has scored 17 goals in all competitions. "I am happy to have scored but also because the team is playing well."
Lionel Messi's stoppage-time goal salvaged a 2-2 draw for Barcelona. Midfielder Ander Herrera put Bilbao ahead in the 20th minute at San Mames stadium before Cesc Fabregas drew the visitors even with a header four minutes later.
Bilbao appeared set to get the win after Gerard Pique scored an own goal in the 80th, but Messi slotted home his league-leading 14th goal in the 91st to split the points. He's one goal ahead of Ronaldo.
Also, Sporting Gijon drew 2-2 at Zaragoza, while Racing Santander at Granada finished 0-0.
Osasuna, which was missing nine first team players from injuries and suspensions, had already lost 8-0 at Barcelona earlier this season.
Before the game, Ronaldo paraded his Golden Boot trophy for Europe's top scorer last season to the 83,000-seat Santiago Bernabeu stadium, which was full despite a first ever midday Sunday kickoff.
Di Maria set up Madrid's 23rd-minute opener when he picked out Ronaldo at the near post with a cross for the Portugal forward to flick into the net.
Osasuna midfielder Raul Garcia caught Madrid's defenders arguing with the referee when he took a free kick quickly and Ibrahima Balde slotted the ball under goalkeeper Iker Casillas to level the score in the 30th.
But any thoughts of an upset quickly evaporated as four minutes later Di Maria sent in another cross for Pepe to head home at the far post. The 23-year-old Di Maria then capped his playmaking display in the 40th when he slid the ball into the area for Higuain to curl into the right side of the net.
Di Maria was taken off on a stretcher for an apparent leg injury early in the second half, but Madrid continued to roll when Ronaldo fired in a penalty in the 54th after defender Eneko Sartustegi was sent off with his second booking for fouling Mesut Oezil in the area.
LONDON (AP) — American goalkeeper Brad Friedel made a number of crucial saves to help Tottenham beat Fulham 3-1 Sunday and stay level on points with fourth-place Chelsea in the Premier League.
Tottenham took a 2-1 lead through goals by Gareth Bale and Aaron Lennon before Friedel — the Premier League's oldest player — saved from Moussa Dembele, Chris Baird, Clint Dempsey, Bobby Zamora and Brede Hangeland to keep his team ahead.
Tottenham substitute Jermain Defoe added a goal in injury time as Spurs' seventh win from eight matches left them trailing Chelsea on goal difference for the final Champion League qualifying berth.
Also Sunday, Bolton and Wolverhampton Wanderers each boosted their chances of avoiding relegation with home wins. Chris Eagles and Ivan Klasnic each scored twice as Bolton avenged last season's FA Cup semifinal 5-0 defeat to Stoke by the same score, while Wolves scored twice in the second half to beat last-place Wigan 3-1.
Dusan Basta put Udinese in front less than a minute in at the Friuli stadium and Antonio Di Natale scored his league-leading eighth of the season in the 64th before Francesco Bolzoni pulled one back for Siena in the 76th.
Based in Udine near the Slovenian border, Udinese's best finish in Serie A was third in 1998 when former Germany international Oliver Bierhoff scored a league-best 27 goals.
Udinese and Lazio have 21 points each, Milan has 20 and Juventus is fourth with 19.
Gomez scored with a header from close range in the 15th minute, when he was well placed to meet Mohamed Amsif's save from Daniel van Buyten's header.
Ribery twisted inside Dominik Reinhardt before slotting past the helpless Amsif to make it 2-0 in the 28th.
Manuel Neuer denied Augsburg an equalizer in the 83rd, with a great reflex save from Edmond Kapllani who was through one-on-one. In a nervous finish for the Bundesliga leader, Anatoliy Tymoshchuk received a straight red card for a dangerous tackle on Daniel Baier in injury time.
Also Sunday, Finland striker Teemu Pukki scored twice in his first Bundesliga start to salvage a 2-2 draw for Schalke at Hannover. Schalke missed the chance to go second and dropped to fifth, three points ahead of Hannover.
PARIS (AP) — Montpellier salvaged a 1-1 draw at Saint-Etienne on Sunday to remain in second place in the French league behind leader Paris Saint-Germain.
PSG can increase its lead to five points if it beats Bordeaux later Sunday.
Romania playmaker Banel Nicolita headed in a cross from Fabien Lemoine to give Saint-Etienne the lead in the 32nd minute. But Montpellier midfielder Joris Marveaux took a headed pass from Olivier Giroud to score from close range in the 57th.
Holman gave AZ the lead in the 11th minute before Maher and Altidore added goals in the second half to secure the victory.
American forward Altidore scored in the 83rd minute with his fourth league goal of the season and eighth overall.
Also Sunday, second-place Twente routed De Grafschaap 4-0, while a hat trick from Jeremain Lens inspired PSV Eindhoven to a 4-1 win over Heracles Almelo.
In the most eventful match of the day, Zambia winger Jacob Mulenga created two goals and scored another as FC Utrecht beat Ajax 6-4 in a game that saw five goals in each half.
AZ has 31 points from 12 games. Twente and PSV have 25 each, while Ajax has 20.
GLASGOW, Scotland (AP) — Celtic substitute Gary Hooper scored with 10 minutes left Sunday for a 2-1 win at Motherwell that took his team above its opponent to second place in the Scottish Premier League.
Michael Higdon put Motherwell ahead in the 11th minute at Fir Park but Celtic leveled three minutes later when Anthony Stokes volleyed in after Georgios Samaras flicked on Kris Commons' corner.