Sri Lanka's decision to field in sweltering conditions in Mumbai during their World Cup match on Thursday surprised many and India batsman Shreyas Iyer felt that the hosts got lucky.

In extremely hot and humid conditions, Sri Lanka captain Kusal Mendis won the toss and in a surprise move invited India to bat first, saying that he expected the pitch to be better for batting second.

Mendis' counterpart, Rohit Sharma, did not mind losing the toss and said he would have batted first nonetheless and "under the lights, it will be nice for the seamers to bowl".

It proved to be a costly decision for Sri Lanka.

India went on to amass 357 for eight from their 50 overs. The undefeated hosts then returned to skittle Sri Lanka for just 55 runs in under 20 overs, with plenty of help on offer for their fast bowlers under the floodlights.

"I think we got lucky," Iyer told reporters when asked about Sri Lanka's decision. "When they won the toss, we were thinking that they would be batting first, especially when you come to Wankhede and play on such a brilliant track.

"And even in the huddle, we decided that if we win the toss, we would be choosing to bat. That didn't go according to plan but we were lucky."

Mendis would not blame the decision to field first for the humbling defeat.

"We had reasons for wanting to bowl first, the wicket was a bit slow," the Sri Lanka captain said. "Unfortunately, there was then a little bit of seam and swing which made it difficult to play at night."