Basically, when I am watching World Cup soccer, am I watching the best demonstation of the sport? Or would watching league matches display a higher level of play? I would think that the best league teams from Spain, England or Italy would have no problem beating the best national teams, since the players would be more accustomed to each other.
Depends on your perspective.
On a purely technical level, the European Cup would probably be the pinnacle of the sport. (Though I’m not as familiar with South American inter-league competition.)
It was also claimed of Liverpool FC when they were winning at this level, their players rarely performed as well when on duty for the national side.
However, IMHO they are “just” club football, albeit excellent. International football outranks it because the stakes and pressures are higher. Players are playing further out of their comfort zone. Once off, no second chance knock-out games. Players may only get one chance in their career to perform at this level.
Many club sides could beat some of these national teams in the final 16. Hell, there are countries that didn’t make the tornament that could do that (Hi Coldfire 
).
But viewed as a competition, this is as good as it gets.
The top club sides in Europe, and possibly South America (I’m not really familiar with the domestic leagues there), could certainly give the top international sides a run for their money. It’s worth remembering that club sides have a greater ability to pick and choose players from almost anywhere in the world. Also, club sides train and play together day-in, day-out, whereas a common complaint of national coaches is that the short time they have to train for international games means little time to teach players to work closely with other players they may never have played with before.
You’ll also often see club sides play lower international sides (such as Hong Kong, Thailand or India) as general practice matches and win easily.
Excellent thread Jackknifed Juggernaut, I was going to post the very same question myself.
In my humble opinion the latter stages of the Champions League are played to a higher standard than the World Cup. Now don’t get me wrong, I love the World Cup, it is a spectacular event and somehow different from all other football competitions - it’s just special - but I can’t help but feel that there was a better standard of football played in the latter stages of Champions League this year (not to mention the big domestic games).
I agree, international football feels a level up from club football, and it is a different game, but I still think if you were to put Real Madrid or Manchester United in this World Cup that they would stand a very good chance of winning.
A top club can draw their players from all over the globe but more importantly the players get to train and play with each other all year round. The players know the capabilities, style, role, and habits of all their teammates inside-out which makes the team a much better and more effective unit. I think this familiarity also gives the coach much more tactical flexibility. I would go as far to say that a weaker club side (player for player) would be able to beat a stronger international side for these reasons. However, because the top club sides are just as strong, or even stronger, (player for player) than the top international sides (even historically speaking), I would have to lay my money on the club side.
Examples (players who play for both teams would be magically duplicated):
[ul]
[li]I think Celtic would beat Scotland. No brainer?[/li][li]I think Arsenal would beat England. Just go through player by player, and then factor in that the Arsenal players have been playing with each other all year (and some for much longer than that) and then also look at the balance of the teams.[/li][li]I think Real Madrid or Bayern Munich would beat Brazil. Munich especially.[/li][li]I think my pub-side would beat China. Just kiddin’. ;)[/li][li]I think Milan (88-90), Liverpool (late 70s and early 80s) and Manchester United (98-99) would all beat France (98-00) (who are about the strongest international side in my life time.)[/li][/ul]
Opinions? What about other teams, both past and present?
Now, if an international side could play in, say, the English Premier League all season, where would they stand then? I would suggest that the best international teams would then be right up there challenging for the title and Champions League. In such a scenario I don’t think there would be much between the top international sides and top club sides, and both would have the advantage over international sides not involved in a domestic league. However, because the club sides could pick their players from all over the globe I still think they would have the edge.
Oops, left off my last paragraph.
In summary, I agree with woolly, club football with the Champions League is probably the pinnacle of the sport but you just can’t beat the World Cup as the greatest, most exciting tournment there is.
You’re counting Arsenal as an English team ObiWan? 
Actually, I was always wondering this myself. I’m inclined to think that Manchester United of a year or two could easily wipe the mat with most national teams.
Don’t some countries have their top club represent them in the Cup, like Nigeria or Ghana? I remember one African soccer team having a club name.
Well several of the African national teams have nicknames as if they were club sides - Nigeria = the Super Eagles, Cameroon = the Indomitable Lions, Ghana = the Black Stars etc., but this link shows the squads for the 2000 African Nations Cup and the players are drawn from clubs all over Europe as well as from local teams.
It’s possible that a single team has supplied all the players for an African national team but I’ve never heard of it. Also there have been some cases where one team has supplied all or most of the players for a national team in Europe.
Every country has got a weak position or side within the team. Italy for example have got problems in midfield, Holland on the right side and have with a lot of left footed midfielders this is a big problem, Brazil is too much left orientated etc. so the are always trying to find an compromise with an lesser player or play someone out of position.
The big clubs in Europe can buy players and will have a better balanced team.
Real Madrid, when motivated ,will beat every team in the World Cup. Practice makes perfect so the clubteams will have an extra advantage.
Technically, the club sides have got it licked (if someone can tell me a better midfield than Giggs, Veron, Keane and Beckham, please do - for the non football knowledge-able, that’s the Manchester United midfield which come from 4 countries), but playing for their country the motivation has to go up (how many of the South Korean team could get a regular place in an European league side?).
So in answer to the OP, the top 3(very ish) club sides of the countries mentioned (and possibly Germany) would beat most of the teams in the last 16 of the World Cup, but as the players are playing for their countries, you never know how well they actually can perform.
Sorry if this is vague, but in football, the result often depends on how well the players play, not how good they are.
The Korean goal scorer Ahn played sparingly for Perugia in Italy and the team cut him soon after he scored the goal that beat Italy.
I think some of the top European teams, either in the Premiership or Serie A are almost like international all-star teams. I think even the World Cup winner would be hard-pressed to beat the champions of those leagues IF you made sure the club teams got to use the players from any national team.
Real Madrids midfield or maybe Arsenal (with Bergkamp as a midfielder). Veron in good shape and a free role adds something to the team, letting him play for and pass the ball to Keane doesn’t.
so true and that’s why I still enjoy the game.