If you happen to know any Arsenal fan, you've certainly heard ad nauseum of Arsenal's unbeaten league season in 2003-2004 and their 49-match unbeaten run in the Premier League. You've also certainly heard that such feat "has never been accomplished before and will never be accomplished again".

Of course that's what Arsenal fans say, and the truth are two quite different things.

Such long unbeaten runs are indeed very rare, but there have been some in modern football history which are even longer and more impressive than Arsenal's.

While winning a league unbeaten and having 40+ unbeaten runs means only one trophy, it's definitely a very rare achievement, and one that the clubs who managed it have every reason to be proud of, especially if we consider that even some of the best squads of all-time failed to achieve such feat. It obviously requires some luck, but also great quality and mental strength.

Let's look at the most impressive unbeaten runs in modern football.

Arsenal 2003-2004 (49 League Games Unbeaten)

After an unsuccessful 2002-2003 season, Arsène Wenger didn't make any major signings and his trust of his players was fully rewarded.

Arsenal took advantage of Manchester United's off season and managed to capture the Premier League title, while not losing a single match in the competition—26 wins and 12 draws. This is even more remarkable if we consider that every other team lost at least seven matches, while Arsenal lost none.

There were moments of brilliance and moments of luck, especially Van Nistelrooy's missed penalty at Old Trafford in stoppage time, which could have ended Arsenal's run. But in the end, Arsenal managed to finish the Premier League season unbeaten, for which they were rightly rewarded with a special version of the trophy.

Thierry Henry had the best season of his life, scoring 39 goals in all competitions.

Despite being unbeaten in the league, Arsenal failed to take advantage of a poor year in European football, having been knocked out in the quarter-finals of the Champions League by Chelsea. The Gunners also didn't manage to win the English Cups, having crashed out to Manchester United in the FA Cup and to Middlesbrough in the Carling Cup.

Overall, Arsenal lost six matches in the 2003-2004 season, but none in the Premier League.

Arsenal would extend their run in the Premier League to 49 unbeaten matches (they'd eventually be stopped at Old Trafford), which is still a record in England.

It was a season where everything clicked and all the players seemed to be in their prime. Success was ephemeral, though, as Arsenal have not won any major trophy since.

Lineup:

GK: Jans Lehman

LB: Ashley Cole

CB: Sol Campbell

CB: Kolo Touré

RB: Lauren

LM: Robert Pirès

DM: Patrick Vieira

CM: Gilberto Silva

RM: Fredrik Ljunberg

SS: Denis Bergkamp

CF: Thierry Henry

AC Milan 1991-1993 (58 Unbeaten League Games)

Arrigo Sacchi's AC Milan is widely recognized as one of the best club sides in history, and one of their most impressive achievements was an incredible 58-match unbeaten run in the Serie A. Milan won the 1991-1992 Serie A unbeaten, with 22 wins and 12 draws. Capello had been appointed as a manager at the beginning of the season, but the team had all been built by Sacchi.

This run is even more impressive if we consider that, at this time, Serie A was by far the strongest league in the world and even teams like Fiorentina, Sampdoria, Napoli, etc...were stacked with world-class talent—Batistuta, Vialli, Maradona, Zola, Careca, etc...

But that didn't stop Milan's Dream Team, who have been the only team to win the Serie A unbeaten to date. Their absence from the Champions League might have helped them in the Serie A, but it is still a magnificent accomplishment.

The backbone of the team had already won the 1989 and 1990 European Cups under Arrigo Sacchi and would win the most important European competition again in 1994, in what marked the peak of a truly great era at AC Milan, who boasted undoubtedly the best team of the nineties and one of the best ever. The Dutch trio (Rijkaard, Gullit and Van Basten) wreaked havoc up front while Maldini and Baresi commanded an unpenetrable back line.

Lineup:

GK: Galli

LB: Paolo Maldini

CB: Baresi

CB: Costacurta

RB: Tassotti

LM: Carlo Ancelotti

CM: Frank Rijkaard

CM: Colombo

RM: Donadoni

SS: Rudd Gullit

CF: Marco Van Basten

Ajax 1994-1995: An Almost Unbeaten Season in All Competitions

Under Louis Van Gaal, Ajax pulled one of the best single seasons in football history in 1994-1995.

They won the Dutch league unbeaten (27 wins, 7 draws) with a ridiculous goal differential of +78 (106-28).

"Anyone can do it in the Dutch League," some might think. Well, think again: Ajax also won the Champions League in 1994-1995...unbeaten. The Dutch didn't lose a single game in the competition and beat AC Milan, 1-0.

This was the only time a team managed to go unbeaten through their national league and the Champions League in the same year, a feat which will probably never be accomplished again.

It was almost a perfect season, as Ajax only lost one game in 1994-1995, in the quarter-finals of the Dutch Cup against Feyenoord after extra time.

With 37 wins, 11 draws and only one defeat (in extra-time) during this season (134-35 in goals), Louis Van Gaal's team's season must be ranked up there with Barcelona's recent sextuple-winning season as the greatest single season of all-time.

Lineup:

GK: Edwin Van der Sar

LB: Frank de Boer

CB: Danny Blind

RB: Michael Reiziger

DM: Frank Rijkaard

CM: Edgar Davids

CM: Clarence Seedorf

AM: Jari Litmanen

LW: Marc Overmars

RW: Finidi George

CF: Patrick Kluivert

Steaua Bucharest 1986-1989 (104 League Matches Unbeaten): The Real Invincibles

When talking about the greatest teams of all-time, this absoutely brilliant Steaua Bucharest team of the late '80s is unfairly forgotten.

Well, the truth is that what Steaua's impressive unbeaten run makes every other run pale in comparison.

If winning one league unbeaten is amazing, what about winning three consecutives leagues unbeaten?!

Steaua won the 1986-1987, 1987-1988 and 1988-1989 Romanian leagues unbeaten! In these three seasons, Steaua collected 86 wins and 16 draws in their national league!

One could argue that the Romanian league is weak, but Steaua was also dominant in Europe in the 1985-1989 period. They won the Champions League in 1985-1986 (just before their three unbeaten leagues run) defeating Barcelona in the final, and they reached the semifinals in 1988 and were again in the final in 1989, losing only to another emergent super-team—Arrigo Sacchi's AC Milan.

The most impressive part is that they did all this with an all-Romanian team (not even one foreign import). It was a miracle generation of Romanian footballers at Steaua, led by a young George Hagi, who took Europe by storm, making Steaua the greatest team of the late '80s and one of the best of all-time. Anghel Iordănescu was the manager behind this fantastic team.

No team comes even close to match Steaua's 104-league matches unbeaten run and probably no one ever will. This side is arguably the most underrated team in football.

Lineup:

GK: Lung

LB: Petrescu

CB: Ungureanu

CB: Bunbescu

RB: Stoica

LM: Iovan

CM: Minea

CM: Lazlo Boloni

RM: George Hagi

CF: Lacatus

CF: Piturka

Closing Thoughts

Very few sides in football history managed to win their national leagues unbeaten; these four teams have all done it in an impressive manner. However, quite curiously, they all experienced a slump after their unbeaten runs: Steaua has never been the same after their golden generation retired, Ajax sold all their players and stopped being a top European team and Arsenal hasn't yet won another major trophy.

AC Milan is still a great club and had another very successful period under Carlo Ancelotti, but they never did manage to reach the same heights again, and they struggled after their brilliant generation left, having even finished 10th in the Serie A on one occasion.

When will another team manage such an impressive unbeaten run? This season, only Manchester United and FC Porto are in a position to do it, but it won't be easy at all. The Portuguese giants are currently in a 36-match unbeaten run in all competitions!