By Braden Phillips

BARCELONA (Reuters) - Having absorbed the body blow of losing striker Radamel Falcao in the close season, Atletico Madrid have emerged as genuine contenders to break the title stranglehold of Real Madrid and Barcelona.

Four straight league wins to go top of the table and a convincing 3-1 victory over Zenit St Petersburg in their Champions League opener mean Atletico are being viewed as a force at home and abroad.

The only blot in a near-perfect start to the season was their narrow away-goals defeat to Barcelona in the Spanish Super Cup after the first and second legs ended in draws.

Atletico's unbeaten record is even more impressive considering last season's top scorer, Colombian international Falcao, left for Monaco in a transfer worth more than 50 million euros (42.18 million pounds) in May.

The silver lining of that deal has been to move the club away from a dependence on one player to a more collective, and ultimately effective, attacking unit.

"I think the club has grown in a major way in the last year and a half, based on confidence, knowledge, stability and contract renewals," coach Diego Simeone said in a news conference ahead of Saturday's match at Real Valladolid.

"This is a more complete team."

Contract renewals are a clear barometer of the confidence Atletico players have in Simeone's project.

Players who might have followed Falcao out of the door in times past have instead opted to stay, boosting morale within the club.

Turkey playmaker Arda Turan extended his Atletico contract by two years on Thursday, amid media reports of interest from Arsenal and Liverpool.

KEY PLAYER

Turan has been a key player during his first two years in the Spanish capital, helping the club win the Europa League, King's Cup and the European Super Cup as well as a third place league finish last season - their highest since 1996.

"The fact that I am so pleased to be staying on is thanks to my team mates and to everything we are achieving together," he said.

Another player who resisted the lure of a big English Premier League payday was defender Juanfran.

As well as keeping hold of established players, the club has made some astute signings. To compensate for the loss of Falcao, they added firepower with David Villa arriving from Barcelona and Brazilian Leo Baptistao from Rayo Vallecano.

In defence they brought in the sought-after Belgium international Toby Alderweireld from Ajax Amsterdam and France international Josuha Guilavogui from St Etienne.

Villa, Baptistao and Diego Costa have formed an exciting attacking trio with Costa, another who turned down a move in the close season, behind only Lionel Messi in La Liga's scoring charts having found the net four times in four games.

Barcelona have an identical record in La Liga having also won their first four, scoring 14 goals and conceding four, while Real Madrid are two points adrift.

Simeone believes the strength of the two traditional powerhouses will make it difficult to surpass them over the long haul.

"I'm not getting too excited yet because La Liga is so long and the economic power they have gives them an edge," he said.

Yet one thing Simeone's side have demonstrated is a tremendous appetite for success, combined with a fighting spirit that could prove decisive later in the season.

In May it will be 40 years since Atletico reached the final of the European Cup where they lost 4-0 to Bayern Munich in a replay.

While they still have a long way to go to match that feat, they are clearly heading in the right direction.

(Editing by Toby Davis)