MUMBAI: India captain Sunil Chhetri has urged fans to be patient with the team and coach Stephen Constantine after the national team's yet another shambolic qualification campaign for the 2018 soccer World Cup.

Long dubbed a 'sleeping giant' of world football by FIFA, India have lost all five of their pool matches in Group D so far in the second stage of the Road to Russia 2018.

They have let in 12 goals while managing to score three and lost even to tiny Guam, the U.S. territory in the North Pacific Ocean with a population of little more than 170,000.

With the matches also doubling up as qualifiers for the 2019 Asian Cup, a loss against the same opponents next week at home would snuff out India's remaining mathematical chances of qualifying for the continent's premier tournament.

India's most prolific goal-scorer Chhetri, however, believes the team is on the right path.

"It's a transition period for the national team. It's always difficult," the 31-year-old told Reuters on the sidelines of a promotional event organised by Puma for his Indian Super League club Mumbai City FC.

"Sixteen boys have made their India debut in the last couple of months. It will take some time.

"It's a period which is going to take a little bit of patience and a little bit of time. It hasn't been easy. We have to work really hard.

"As players we are trying our best to give as much as possible and I will keep doing that."

It remains a mystery for many why a country of 1.2 billion, with a rich soccer history to boot, has not featured in World Cups yet.

The All-India Football Federation has brought back Constantine for a second stint with the national team after the Englishman guided Rwanda to their highest ever FIFA ranking of 64.

India started well under him by beating Nepal to progress to the second round of the combined 2018 World Cup and 2019 Asian Cup qualifiers before things took a turn for the worse.

Chhetri, who has scored two of the three goals India have managed in their five pool matches, had no doubt Constantine was the best man for the job.

"He is somebody who really works hard. The coach needs time. We have to be patient," Chhetri said.

"It's not only him, when the team loses it's because of all of us. It's not fair just picking on one person."

Chhetri, who missed the inaugural edition of the franchise-based ISL last year, has been in sublime touch in the second edition and has scored six goals in four matches for his team.

He was unavailable for a few matches due to national team duties and hoped the ISL can merge with the pre-existing national championships, I-League, in the future to make it easier to synchronise India's calendar with FIFA.

"Personally, yes, there should be one league in India. The I-League, the ISL, the Federation they all want (good) things for football in India," Chhetri said.

"I just hope they can sit together, talk it out and have a plan where there is just one league maybe in future and have one calendar. I'm sure they are going to do it soon."