Alastair Cook's record-breaking 23rd Test century is an "amazing achievement", says his new opening partner Nick Compton.
Captain Cook set a record for England Test centuries on the second day of the third Test as the tourists closed on 216-1 in reply to India's 316.
Compton, who hit his maiden Test fifty, said he had "the best seat in the house" to watch Cook's unbeaten 136.
"It's amazing how he hasn't made a mistake," said Compton.
The pair shared an opening stand of 165 and Somerset batsman Compton, playing only his third Test, acknowledges that playing alongside Cook is helping him perform.
"To watch that ball after ball, it does give me a lot of confidence that I can spend time getting in," he said.
"Even though he's outscored me and been the dominant partner, I've taken a lot from the fact that we've got to those milestones and from a team perspective that's all you can do to set the innings up.
"I thought it was a really good partnership up front and the way he's been playing the last couple of weeks has been fantastic."
Cook's innings was his fifth century in five matches as captain, while he also became the youngest player, at 27 years and 347 days, to reach 7,000 Test runs in the process, beating India legend Sachin Tendulkar's record.
Compton added: "It says a lot about his hunger and determination, the fact that he's been so consistent over a period of time at a young age.
"A lot of batsmen only really find their feet at 28, 29, and the fact that he's found his feet at a very young age and done it for so long is amazing.
"The stats speak for themselves - to be ahead of Sachin Tendulkar at this stage is an amazing achievement."
Cook stands 20th on the all-time list of Test centurions, which is topped by Tendulkar with 51.
Former England captain Michael Vaughan said Cook had impressed him since first walking into the England dressing room and backed the Essex man to surpass the records of Test greats such as Ricky Ponting and Rahul Dravid.
He added: "He's a terrific player. It's quite bizarre to think he's got 7,000 runs and 23 centuries and he's only just starting to get recognition.
"He's certainly going to break all of the English records. He will become a great.
"In Alastair Cook, England have got an outstanding young man and we're in safe hands for many, many years."
Geoffrey Boycott, one of four England batsman with 22 Test centuries to his name - alongside Walter Hammond, Colin Cowdrey and Cook's team-mate Kevin Pietersen - says Cook will not be focusing on the achievement.
"I don't think it will be such a big deal to him," Boycott said. "At his age he's going to get quite a lot more unless he has a serious illness or injury.
"He's in the best years of his life and will automatically play, he has a good technique and should be well on the way to 40 hundreds by the time he's finished.
"The great side to him is the fact that he doesn't allow any bowler to get himself out of his comfort zone. He plays perfectly as an opening batsman.
"He has looked in no trouble whatsoever (in Kolkata); he's got these spinners in his pocket. I haven't seen at any time that this lot look like they will get him out."