The defending Spanish League champions aren't exactly playing like "champions" at the moment.

The team's superstar forward and arguably best player in the world in Lionel Messi is still out with a leg injury. Goalkeeper Claudio Bravo recently returned from a calf injury, and Luis Enrique's squad isn't keeping the ball out of the net like he knows his team is capable of.

Barcelona is currently 5-0-2 with 15 points. That's tied for second place with Real Madrid and Celta Vigo while Villarreal is in first place with 16 points. Barcelona only had four defeats all of last season in 38 La Liga matches but already have two in seven matches this season. Barcelona has now lost two of their last three games.

The biggest issue, other than Messi's injury, has been defense. Last season Barcelona was the No. 1 defensive team in the league by a mile. They allowed only 21 goals against the entire season. For perspective, Real Madrid allowed 38 goals against last season. So far through the first seven games of this season, Barcelona has conceded nine goals. If this trend continues, Barcelona will allow on average 48.8 goals against this year, more than twice as much as all of last season.

There is still no definitive date on when Messi will return for Barcelona. Speaking of Messi, he still has to resolve a little tax issue with the Spanish courts. That shouldn't interfere with his playing time at all, but it's just another distraction.

Barcelona is tied with Real Madrid in the standings with 15 points, but Real Madrid has yet to lose a single game yet this season. Even more glaring, Real Madrid's defense has been much improved, and the team hasn't suffered despite losing goalkeeping legend Iker Casillas in net. Cristiano Ronaldo is in a bit of a goal scoring slump by his standards, but Karim Benzema has been on fire lately.

Now is the time for Neymar and Luis Suarez to shine. Neymar is an incredibly gifted dribbler, and Suarez's passing has been improving every year. Suarez has also scored numerous clutch goals for Barcelona over the years. Neymar and Suarez have certainly benefited from having Messi by their sides, but they now have to show they can succeed without the Argentine superstar on the field.

Barcelona will face Rayo Vallecano in their next game.

Another factor to consider is competition. It's normal to see the usual Real Madrid-Barcelona rivalry going on atop the standings, but Barcelona has their hands full this year. Atletico Madrid has a strong squad this season, and Villarreal is playing great. Barcelona isn't going to cakewalk their way to a 24th La Liga title with so many quality teams this year.

There's still plenty of time for Barcelona to regroup and win a second consecutive league title, but it won't be very easy. This year has a few more challenges for Barcelona because of injuries, so it will be very interesting to see how it ends.

Follow Damon Salvadore on Twitter @DamonSalvadore1