5 Obstacles for Barcelona in the Hunt for Champions League Glory in 2015-16

With the start of pre-season, comes the start of hope: Hope for teams across Europe they can wrestle Barcelona's Champions League trophy away from them, and hope at Camp Nou they can keep a tight grip on it.

They are, having won the treble last season, the best team in Europe and will be favourites to land the trophy against next season.

Here we look at five obstacles for them on the hunt for glory.

Europe's Elite

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The likes of Bayern Munich and Real Madrid will be looking to strike back against the might of Barcelona.

Neither side has yet made any impressive moves in the transfer market, but both are likely to do so as they try and "level up."

Manchester United, a traditional giant of Europe, have done good business already, bringing in the likes of Bastian Schweinsteiger, Memphis Depay and Morgan Schneiderlin.

Jose Mourinho's Chelsea are a young team, with players such as Eden Hazard, Oscar and Willian, who continue to develop, and it would be no surprise if they went in search of more recruits.

One of which seems to be Pedro, with Mourinho calling the winger up, according to Sport.

With Barcelona banned from registering new players before January thanks to their transfer ban, the likes of Arda Turan and Aleix Vidal cannot compete yet, either.

Inspiring the Players

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Some of Barcelona's stars, such as Lionel Messi and Andres Iniesta, need no encouragement.

They are serial winners who have triumphed in the Champions League and on other stages time and time again.

That's all well and good, and they will be key influences in the new season as you would expect.

What will be interesting to see is the hunger of Neymar and Luis Suarez, who have now enjoyed glories the likes of which they had not lived through before.

The former came out with a strong message to Barcelona fans, saying he was determined not to slow down. In an interview with Sport, Neymar said:

"

The season has been wonderful, something incredible, but I always want more. I'm never satisfied, I maintain the same hunger to keep winning more leagues, Champions Leagues, Copas. The people can be calm because we want more.

"

Although it's hard to doubt Neymar's sincerity, the mental relaxation at already having won the trophy, the quenching of the thirst, might affect Barcelona's intensity levels.

History Suggests It's Hard

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Barcelona have been dominant in the Champions League in the past decade, winning it four times in 10 years.

But winning the trophy two years running has proven difficult. Not just for the Catalans, but for any side.

In fact, you have to go back to 1990 for the first time any side was able to retain the trophy, before it even turned from the European Cup to the Champions League.

AC Milan were the team that did it, beating Steaua Bucharest in 1989 and Benfica the following season.

Before them, it was Nottingham Forest, a decade earlier, triumphing in 1979 and 1980.

Although they won't physically feel the weight of history, the data suggests it is an obstacle.

Working out How to Stop Them

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The world watched as Barcelona crushed Juventus with Luis Enrique's counter-attacking style.

And now each of the club's opponents will be working out the best way to stop them.

They have made themselves No. 1 targets, and more than ever, clubs will face Barcelona explicitly looking to stop them rather than go out to win themselves.

Jorge Sampaoli's Chile did a good job of punishing Lionel Messi during the Copa America final, but he will be in a different role for Barcelona.

Stopping Messi has been a problem to which nobody has consistently found a solution, bar perhaps Chelsea, whom he has never scored against.

It will continue to be asked, probably unsuccessfully, but with everybody going all out against Barcelona, things won't be easy for the champions.

Exhaustion

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It's been all go for a lot of Barcelona's players for a while.

Many of them featured at the World Cup in 2014 before playing a full season with the club, in which they reached all the finals they possibly could.

Some of the team, including Lionel Messi, Neymar and Javier Mascherano, then went to the Copa America, meaning they've endured another summer without rest.

They will also have their eye on next summer, with a centenary edition of the Copa America in the pipeline, along with the European Championship.

In between, they have a season ahead, and if Barcelona play as well as they did last year and go as far as they can in all competitions, they will play 65 games.

That would be a club record for most matches in a season, per Sport.

Previously, the largest number of games was 64 in 2011-12.

There is also the matter of the Club World Cup, which takes place in Japan.

After Real Madrid went to the same competition last winter, their unbeaten streak came to an end and their season fell apart.

A lot of travel and a lot of football leaves a lot of players very tired, and this could be another obstacle on the route to Champions League glory.