* Del Potro and Ferrer through to second round
* Wins also for promising players Raonic and Dimitrov (Adds quotes, details, other results)
By Sonia Oxley
LONDON, June 25 (Reuters) - Juan Martin del Potro provided some encouragement for the rest of the chasing pack in the men's game at Wimbledon on Tuesday.
Apart from single triumphs by the Argentine and Britain's Andy Murray, the trio of Roger Federer, Rafa Nadal and Novak Djokovic have won every one of the last 33 slams.
The Argentine, who reached the second round with a 6-2 7-5 6-1 victory over Spain's Albert Ramos, is in a group of players always waiting to capitalise on slip-ups by the triumvirate.
Nadal has already tumbled out at the All England Club, suffering a shock first-round loss to Steve Darcis on Monday, which spells good news for the cluster of 'best of the rest' players.
Murray, who has reached three of the last four grand slam finals, has also opened up a gap with the chasing pack.
"All the players can beat the top 10 players, the top four, the top five," said Del Potro, whose 2009 U.S. Open victory and Murray's 2012 win at the same tournament are the only times a non-'Big Three' name has won a major since 2005.
"I knew after three or four years they win every grand slam, the same players... It's really difficult (to) break that name on the big tournaments," he told a news conference.
"But, of course, I'm trying. I like to play the grand slams. They are (the) longest tournaments, and you can play maybe a bad match and survive and that gives confidence for the next rounds. In the grand slam during 15 days, everything can happen."
Eighth seed Del Potro, who missed the French Open because of a virus, will face Canadian Jesse Levine in the second round after shaking off the rust to beat left-handed Ramos.
Having sailed through the first set, he made hard work of the second when, having broken and established a 5-2 lead, the net-shy Argentine was caught out by some drop shots.
The towering Del Potro looked uncomfortable venturing away from his usual domain behind the baseline and a combination of Ramos forcing him forward and a double fault allowed the Spaniard to break before holding to level at 5-5.
Something then clicked for the Argentine as he found his range with a series of unreachable cross-court forehands and powerful serves and he won seven successive games before Ramos held to make Del Potro serve out the match.
Another of those seeking to gatecrash the elite club is David Ferrer, the fourth seed who is seeking his maiden grand slam trophy after appearing in his first major final earlier this month when he was beaten by Nadal at the French Open.
The Spaniard beat Argentina's Martin Alund 6-1 4-6 7-5 6-2 having fallen heavily twice on a surface far less suited to his defensive game than the clay where he shone at Roland Garros.
"I have a little bit of pain on my ankle. But it's okay," he told a news conference, adding that his left ankle was slightly inflamed.
At 31, Ferrer has been around too long to be termed 'up and coming' unlike Montenegro-born Canadian Milos Raonic.
Seeded 17th, Raonic is a big-serving 22-year-old who looks destined to build on three fourth-round appearances at grand slams in the last two years after delivering 19 aces in a 6-4 6-3 6-3 win over Argentine Carlos Berlocq.
Another promising 22-year-old, Grigor Dimitrov of Bulgaria, made light work of Italy's Simone Bolelli in a 6-1 6-4 6-3 victory.
Czech Tomas Berdych, whose pursuit of a grand slam title has - like Ferrer - been halted by Nadal to whom he lost the 2010 Wimbledon final, also booked his place in the second round on Tuesday.
The seventh seed went through after a straightforward 6-3 6-4 6-4 triumph over Slovak left hander Martin Klizan. (Reporting by Sonia Oxley; Editing by Ken Ferris)