Gambhir (167) slammed his fourth successive century on the opening day of the second Test against Sri Lanka on Tuesday, and Sehwag, who himself scored a blistering 131, said his younger opening partner can score another hundred in the next match.
"He (Gambhir) is best opener India has after Gavaskar. He has hit four successive Test centuries and already has eight Test centuries in 25-30 Tests. I think with the kind of form he is in, he can slam a ton in the next Test as well," Sehwag said, after India piled 417 for 2 on the opening day.
"He was in good form and hitting well. So we were still scoring at over three, and his boundaries took the pressure off me and I could wait before playing my shots," he said.
Sehwag was seen interacting with Gambhir after the left-hander foozled a shot against Muttiah Muralitharan in the morning session.
Asked what he told his Delhi team-mate, Sehwag said, "I told him to think big. You are good enough to score four successive centuries. Stay three hours and you will automatically get a hundred."
Sehwag said India will look to pile 700-plus runs on Wednesday to put enough pressure on Sri Lanka so that they crumble.
Sehwag and Gambhir were involved in a blistering 233-run opening stand that proved the bedrock of India's stunning batting display on the opening day of the second Test and the right-hander insists his teammates cannot relax or relent yet.
"We are in a positive frame of mind. We have scored a good total for the opening day and scored at a good rate (4.63) to boot. Tomorrow, we will try to get 700-800 and then put pressure on the Lankans and get those 20 wickets," he said.
Sri Lanka got just two wickets after a hard day's toil but Sehwag believes his bowling colleagues can overcome the lack of life on the track and bowl India to victory.
"We bowled out Australia twice on a placid Mohali track [last year] and there is no reason why we cannot do it here. I hope Zaheer (Khan), Harbhajan (Singh), (S) Sreesanth and (Pragyan) Ojha will do it for us," he said.
Sehwag's own knock was a well-paced compilation, as the Delhi dasher overcame a wobbly morning hour before blooming into his aggressive self.
"With little moisture in the air I knew the ball would do something and I had to be careful. They had three spinners and I fancied my chances against them. So I took time and concentrated a lot before playing my shots," he said.
"In Ahmedabad they dropped me and here too they grassed one. I told myself to play the first 8-10 overs and concentrate hard. I tried to leave balls outside off-stump and it's only after first hour that I played my shots," said the explosive opener, who got a life on zero, when Mahela Jayawardene dropped him off Chanaka Welegedara."