Real Madrid roared back to form with a 4-2 victory over Monaco at the Bernabeu, while Chelsea and Arsenal played out a cagey 1-1 draw at Stamford Bridge in Wednesday's Champions League quarterfinal, first leg ties.
Madrid, still reeling from last week's King's Cup final defeat by Real Zaragoza and the weekend league reverse by Athletic Bilbao, were jeered off at halftime as they trailed to Sebastien Squillaci's soft 43rd-minute goal.
But, just like defending European champions AC Milan 24 hours earlier, the Primera Liga leaders responded with a four-goal blast to close in on a semifinal showdown with either Arsenal or their English counterparts Chelsea.
Ivan Helguera eased the tension in a subdued Bernabeu stadium in the 51st minute, getting the final touch to David Beckham's inswinging corner.
Released from their shackles, the nine-times European champions then ripped into Monaco.
French midfielder Zinedine Zidane fired Real ahead in the 70th minute after Luis Figo's fierce effort was blocked by Monaco goalkeeper Flavio Roma and seven minutes later Figo made it 3-1, heading in after Roma had clawed out his penalty.
Ronaldo, who had earned the spot kick, then converted a defence-splitting pass from Zidane to seemingly snuff out Monaco's resistance.
But the final drama belonged to Real's former hero Fernando Morientes. Unwanted at Madrid, the striker on loan in the principality powered in a trademark header that gave his side a glimmer of hope for the second leg.
Real's 26-year-old striker Raul set a new record of 86 Champions League appearances, although he missed several good chances to add to his tally of 44 goals in the competition.
"We started the game nervously," said Real coach Carlos Queiroz. "The goal took a long time coming but after we we calmed down and started passing the ball."
Monaco coach Didier Deschamps said his young side ran out of steam after a good start. "We had a very bad half hour in the second half," he said. "Their superiority was never in doubt but we still have hope."
Real's David Beckham and Monaco's Lucas Bernardi will both miss the return in France after picking up bookings.
In west London, Chelsea were left frustrated again as they failed for the 17th time in a row to beat city rivals Arsenal.
After three 2-1 defeats by Arsene Wenger's side this season, Chelsea were given hope in the 53rd minute when Iceland striker Eidur Gudjohnsen charged down a casual clearance by Arsenal's German keeper Jens Lehmann and shot home from an acute angle.
But Arsenal, who have gone 29 league matches unbeaten since the start of the season to lead the premier league table by nine points, were back on level terms six minutes later.
England defender Ashley Cole delivered a measured cross and French midfielder Robert Pires placed a clinical header just inside Marco Ambrosio's post.
It was the first goal Chelsea had conceded in the Champions League for 561 minutes, the third longest streak in the competition's history, and one that may prove costly.
"We were desperate to keep a clean sheet," Gudjohnsen told Sky Sports. "You realised straight away it was an important goal, you could see that from their reaction as well."
Worse was to follow for Claudio Ranieri's side after 83 minutes as defender Marcel Desailly was sent off for his second yellow card after a late tackle on fellow French World Cup winner Patrick Vieira. He will miss the second leg.
"We have a good opportunity now," said Wenger, who is looking to take Arsenal to their first Champions League semi-final. "When we gave the goal away we needed to show a lot of character. It is a great result for us."
Ranieri, who looks destined to lose his job at the end of the season, was typically defiant. "They still have to kill us it's not finished yet," said the Italian.
On Tuesday two goals from Brazilian Kaka inspired champions AC Milan to a 4-1 thrashing of Deportivo Coruna at the San Siro, while Porto put themselves on course for a possible semi-final with the Italians after a 2-0 home win over Olympique Lyon.
