Chasing 364 for a win, Sri Lanka were shot out for 194 in 39.2 overs and Mathews did not hide his disappointment after trailing the five-match series.
"Our batsmen's approach has to be a very positive, look to score runs whether spinners or pacers, we should look to score runs all the time. Chasing 360-plus you need to show a different approach in the first 10 overs. I thought our downfall was the first 10 overs while batting," Mathews told reporters at the post match interaction.
"The wicket was very good and we could have chased it if we had wickets in hand. I thought in the first 10 overs the approach while batting especially was not that great when we're chasing 360-plus. We did not go off to a go start, at least we could have showed some good intent at the start," Mathews reiterated.
The Lankan skipper further said they always knew India would be a tough opposition at home.
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"It's a tough place, very rarely teams come in and beat India. It's an opportunity to prove we are. Wickets here are pretty flat and batting line-up is huge and they have a formidable bowling. They have been playing well in ODIs and T20Is."
"We dropped them but you cant take anything away from they way batted. They looked to challenge our bowlers all the time," he said.
"They played some good shots. Rahane, Dhawan batted brilliantly and they all came into the party. Once again our inexperience showed. We're a bit rusty today in the field. We can only improve from here," the all-rounder concluded.