Can Barcelona really go the Liga season unbeaten?

Something unusual happened last Wednesday. For the first time since double defeat in their Supercopa series against Real Madrid in August, Barcelona lost a game of football. In La Liga, however, normal service was resumed on Sunday and their record remains unblemished after 20 rounds of matches.

Wednesday's night's narrow loss to Espanyol may yet prove anecdotic as the two teams meet again at Camp Nou on Thursday in the second leg of their Copa del Rey quarter-final tie, when Ernesto Valverde's men will be big favourites to overturn the 1-0 deficit.

"They did well, we congratulate them and we will see them in the return," Valverde said after the game at Cornella. "We hope that our fans can help us at Camp Nou."

The Barca boss will not be overly concerned. His experimental side still should have won the match and may well have done had Lionel Messi converted from the penalty spot, the Argentine's spot-kick saved by Diego Lopez prior to Oscar Melendo's late winner.

Valverde will pick stronger sides in the Champions League and La Liga, and in those two competitions, Barca remain unbeaten. The Blaugrana face Chelsea in the last 16 in Europe after four wins and two draws in the group stages, while they top the Primera Division with 17 victories out of 20, having returned to winning ways with an impressive 5-0 victory at Betis on Sunday.

In 2012-13, Barca racked up 55 points after 19 rounds of games under Tito Vilanova, winning 18 and drawing the other (2-2 at home to Real Madrid). However, they did go on to lose twice in La Liga that season - a 3-2 loss at Anoeta against Real Sociedad in round 20 and a 2-1 to Los Blancos at Santiago Bernabeu a few weeks later.

Despite difficulties as Vilanova took time out for cancer treatment, that season remains Barca's best in terms of points as the Catalans equalled the record of 100 set by Jose Mourinho's Madrid in the previous campaign.

Like Barca in 2012-13, Madrid also lost two league matches in their best season - a 1-0 defeat at Levante early on and a 3-1 loss at home to Barcelona in the 16th round of matches.

Barca lost five league games in Pep Guardiola's first season as coach (2008-09), although two of those came after the title had been won and as the Catalans rested players ahead of the Champions League final against Manchester United.

And in 2009-10, there was only one loss for Pep's side as Barca won with 99 points, the sole defeat coming in a 2-1 reverse away to Atletico Madrid in the 22nd round of matches (in February). There were also 31 wins and six draws en route to what was a record total at the time.

In 2010-11, Barca then lost just twice in La Liga, with defeats at home to Hercules in September and away to Real Sociedad in April as the Blaugrana finished with 96 points. So on several occasions, the Catalans have come close to an 'invincible' season in the Primera Division, especially in 2009-10.

This time, with tough trips to Anoeta (where Barca had not previously won since 2007), Atletico and Real Madrid all safely negotiated, they may never have a better chance of going through a league season undefeated. They are already more than halfway there.