It was a symbolic yet defining moment. 

As Barcelona continued to make every effort to come back from a 2-1 deficit in a thrilling "El Clasico" that was pockmarked by lightning, thunder and torrential rain, Lionel Messi was caught on camera shivering on the pitch like a feeble pensioner. After a vain attempt to resist the cold, the six-time Ballon d'Or winner rushed to the sideline and swapped his drenched shirt for a dry one. 

However, a change of kit failed to reverse Barca's ailing fortunes. Despite a late siege to the Real Madrid goalmouth, a numerical advantage after a red card and a shot off the bar by Ilaix Moriba, Messi and his exhausted teammates still fell short in the end and wasted their most presentable chance to reclaim the top spot of La Liga.  

Amid all the doom and gloom, Messi has now failed to score in seven straight El Clasicos, the longest drought of his career. To make matters worse, as the Argentinian superstar is yet to renew his contract, it could be the last time that he played in this significant fixture.

At a rain-soaked Alfredo Di Stefano Stadium, Karim Benzema put the defending champions in charge with a delightful backheel while a deflected Toni Kroos free kick doubled their lead in the 28th. Barca pulled one back through a lively Oscar Mingueza, but had a penalty appeal waved away by referee Gil Manzano when Martin Braithwaite went down following a challenge by Ferland Mendy. 

"First of all I want to say in the first half we weren't good, attacking or defending," Barcelona coach Ronald Koeman fumed. "Second half we improved and I only ask that the referees get decisions right. It's a penalty and four minutes of extra time when the referee had three minutes with his shoulder issue. The penalty is clear." 

The sentiment was echoed by defender Sergi Roberto, who was quoted as saying by the Marca after the game, "The non-call on Braithwaite? I think Mendy touched him. I was upset that it wasn't reviewed." 

Messi, who was denied by the post at the end of the first half, also vented his frustrations at Manzano. According to Spanish media outlet Catalunya Radio, the Barca captain was overheard shouting at the official, "Referee! Speak well, with respect!"

Messi's exasperation is understandable. Barca looked to dominate possession but were strangely powerless to cope with Real's counter-attacks. Controversial refereeing decisions, couple with the slippery conditions, set up the frantic finish, but Real rode the luck and weathered the storm. 

The calamitous loss to Real not only brought Barca's 19-game unbeaten run to an end but also directly handed the initiative in the title race to their arch-rivals, who have won three in a row in El Clasicos for the first time since 1978.  

For Zinedine Zidane's uplifting side, the extremely important win capped an incredible week after their Champions League quarter-final triumph against Liverpool in mid-week. Real has hit top gear at a crucial stage of the season both domestically and in Europe. 

For Barca and Messi, however, the self-defeating habits of losing their most important games of the season continue to sting, having already been knocked out of the Champions League.  

Next up for them is the Copa del Rey final against Athletic Bilbao, and the pressure is building on Koeman's side. If they choke again, the setback could develop into another full-blown crisis.

Elsewhere on Saturday, Bundesliga leaders Bayern Munich slumped to a 1-1 draw at home against Union Berlin, while French champions Paris Saint-Germain cruised to a 4-1 win at Racing Strasbourg. Zlatan Ibrahimovic was sent off as AC Milan earned a hard-fought 3-1 win at Parma in Serie A. 

In the Premier League, 10-man Leeds United beat runaway leaders Manchester City at Etihad Stadium, Liverpool came from behind to outclass Aston Villa, and Chelsea made amends for last weekend's 5-2 loss to West Brom by overwhelming Crystal Palace 4-1.