Ecuador, Uruguay are reeling at the wrong time in World Cup qualifying

South America's World Cup qualification campaign is a marathon. With a total of 18 rounds played over more than two years, stretching over three club seasons, it is all but impossible to maintain consistency from the first kickoff to the final whistle.

The early pacesetters of the current campaign know this all too well. Ecuador were out of the blocks at a blistering pace, winning their first four games. The only rivals at the top of the table were Uruguay. After six rounds, a third of the way through, they were level on points and only separated on goal difference. By the halfway stage, Uruguay were out in front, but Ecuador had dropped to third. Even so, they still seemed to be sitting pretty. Historically, 28 points have always been enough for direct qualification, with 27, 25 or even 24 sufficient to grab the playoff spot. And with 50 percent of the campaign still to come, Uruguay already had 19 and Ecuador 16. Surely the pair would be able to cross the line in relative comfort.

The table now, going into Thursday's 15 round, looks very different -- worrying for Uruguay, and downright alarming for Ecuador. The Uruguayans are third, but only a point clear of the playoff spot. Ecuador, meanwhile, are down in sixth and in real danger of missing out on Russia altogether.

What makes things worse for the early leaders is that on Thursday they are up against the continent's "Big Two." Ecuador visit Brazil while, in the undoubted tie of the round, Uruguay host Argentina.

This may not be a good moment to face the Argentines, who themselves are scrambling desperately for points. But they have a new coach - Jorge Sampaoli, who did such exciting and impressive work with Chile before enjoying a fine debut season in Spain with Sevilla. There is genuine optimism that finally Argentina have a coach able to get Argentina's star-studded attack to click together -- the fact that the team have scored just 15 goals in 14 games is a sad indictment of a side that has been punching far below its weight.

Ecuador, meanwhile, travel to meet a Brazil side in party mood. With four rounds still to go, Brazil have already made sure of their place in Russia -- a consequence of the superb work done last season by new coach Tite, who took a struggling side and led it to eight consecutive wins. Thursday's match is in Porto Alegre, his hometown. In all of their history, Brazil have never lost a World Cup qualifier on home soil. It would be one of the biggest shocks in the continent's footballing history if that proud record were to fall to the Ecuadorians.

The chances are, then, that going into matchday 16 next Tuesday, the table is going to look even worse -- if not for Uruguay, then almost certainly for Ecuador.

What has gone wrong with the two teams who set the early pace?

In the case of Ecuador, after those four opening wins the next 10 games have brought just two victories. There are concerns that the team no longer gains the same advantage from playing its home games at the altitude of Quito, since an increasing number of players are based abroad and have lost familiarity with the conditions. More to the point, perhaps, is that Ecuador are heavily dependent on a restricted group of players. If they lose form and fitness, then performance suffers. One of the stars of the early wins was Swansea winger Jefferson Montero, who has been badly affected by a series of injuries. Key centre-forward Enner Valencia appeared to lose form and confidence in England.

And centre-back has been a problem position for a while. Senior defender Frickson Erazo ran into injury problems. Along came the duo of Arturo Mina and Luis Caicedo, who were so impressive last year as little Independiente del Valle made it all the way to the final of the Copa Libertadores. They were both sold abroad, but their moves have not proved a success. They, too, have lost form and coach Gustavo Quinteros is still searching. His patched up defence will surely be severely tested by the Brazil forward line.

Uruguay also have defensive problems. Coach Oscar Washington Tabarez is emphatic about his team's model of play. Uruguay have to operate within their limitations and he fully expects the opposition to have more possession. Defensive solidity, then, is essential. But the side has started leaking goals -- with nine conceded in the last three World Cup qualifiers, all defeats. In June the team collected two more defeats in friendlies away to Ireland and Italy, letting in three goals each time.

The problem may well be in the central midfield positions, where one of the team's stalwarts, Egidio Arevalo Rios, is now 35. Will he be trusted to start Thursday's game against the likes of Lionel Messi and Paulo Dybala? Or has the time come for bolder solutions? Both Tabarez and Quinteros could be forgiven for wanting to turn the clock back to a time when their teams seemed to be coasting to Russia. But it is form over the next few weeks which will determine whether or not they make it to the World Cup.