Who are the power countries of tennis? Are they the ones who perform well in the Davis Cup regularly?
The Davis Cup site has the rankings of countries displayed here—it is a good indicator of the depth of the countries' strength in the game.
Though most of the top players compete for their country, it is not a guarantee that everyone will sign up.
Hence, though the list gives a good feeler for the power list, this might be 10-20 percent off the mark.
Who are the players who present the best chances from their country in terms of potential ability to break into the Top 10 or even Top 20 list?
The list contains fifteen countries as present on the Davis Cup listing and sorted in the descending order of the (top) player rankings on the ATP tour.
Because of this cut-off, Great Britain drops off the list—their ranking is a lowly 35.
Similarly, teams like Kazakhstan and Israel drop off since none of their players appear in the Top 50 of the ATP Tour.
Let me know if you can add other countries and their representatives—I will add to the list.
Jurgen Melzer of Austria has been making the odd upset here and there to come to a ranking of 35 in the ATP Tour.
In the Davis Cup however, Melzer and his team have reached a high of nine!
Italian Andreas Seppi with his team-mates may not have made their presence much in the ATP rankings, even though he is ranked 26th in the circuit.
The Italians have shown that the team's performance in the Davis Cup is much more than what the rankings of its players show.
Though Philipp Kohlschreiber is the highest-ranked player in Germany, Florian Mayer has been the primary reason why Germany enjoys a ranking of 11 in the Davis Cup.
Ranked at 25 in the ATP Tour, Mayer has silently been improving his game to reach greater heights.
Croatia has been fortunate to have Marin Cilic play for the team whenever required.
Though holding a ranking of 16, Cilic has brought his team to a ranking of seven in the Davis Cup—a great achievement indeed!
Milos Raonic of Canada has punched above his weight for his country to achieve great laurels.
An individual ranking of 14 has not prevented Raonic from taking his team to the 12th position in the ATP rankings.
John Isner is the current flag-bearer of the USA both in the individual rankings where he is 12th as well as team rankings, where the USA is sixth.
After Andy Roddick's retirement, it will be Isner who has to don the mantle of motivating the rest of the Americans on circuit to greater heights by his performance on court.
Juan Martin Del Potro is ranked eighth in the world but his team is ranked above him at third.
A Grand Slam winner early in his career, Del Potro has not managed to reach greater heights in his career due to injuries and lack of form.
The Czech Republic enjoys the second spot in the team ranking, next only to Spain thanks to the efforts of its seventh-ranked player in the world, Tomas Berdych.
Berdych—as well as his fellow countryman Radek Stepanek, who is possibly the only player with a ranking in Top 50 in singles and doubles—has helped the Czech to climb to great heights.
Jo-Wilfried Tsonga appears on the ATP rankings at six while his country appears at No. 5 on the team rankings.
Again, another team that has good depth in its team, France has three players in the Top 20 ATP rankings.
"The Djoker" has also been very consistent in appearing for his country whenever possible.
Novak Djokovic missed out on an Olympic medal but otherwise he has ensured the best always for his country.
This is one of the few reasons that has made Serbia climb to No. 4 on the rankings chart.
The depth of the Spanish Davis Cup team makes it easy for them even when Rafael Nadal is not playing.
If Nadal makes it to the team, it becomes awesome.
Imagine a team that has No. 5 David Ferrer and No. 11 Nicolas Almagro other than Rafa!
No wonder they are ranked No. 1 in Davis Cup consistently.
Roger Federer. Switzerland has benefited by the regular presence of "Fed Ex" on their team whenever the Davis Cup competitions are scheduled.
It is a very compelling reason that has made Roger drop out of the Davis Cup team.
However good he is, Federer can win only two matches in a tie and that has been the reason why Switzerland has not been able to rise higher in the Davis Cup rankings.