Alastair Cook announced that he will retire from international cricket after the fifth and final Test of the home series against India. The opener was reputed for his ability to grind out big scores in the toughest of situations.

In all, the tough left-hander has scored 32 Test hundreds and 56 half-centuries. Though slightly inconsistent in the past couple of years, but his appetite for big runs has remained undiminished, as he showed with a couple of double centuries in 2017.

Here are five of his greatest, career-defining knocks.

104 v India, Nagpur 2006

Following consistent performances for Essex in the red-ball format, Cook was promoted to the Test side and played his debut game, aged 21, in India. He was flown from an A tour in the Caribbean as a last-minute replacement and battled jet lag to make an instant impact. In the first innings he scored a gritty 60, and followed it up with an even better 104 not out in the second innings. All this against an attack featuring the likes of Anil Kumble and Harbhajan Singh.

110 v Pakistan, The Oval 2010

Cook's form was faltering a little bit. He came into the game with scores of 7, 23, 29, 8, 12, 17 and 4. There were murmurs that replacements were being considered and Cook's critics grew louder when he scored just 6 in the first innings of the Oval Test. But he dug in and produced a fantastic 110 which almost changed the course of the Test. But although England went on to lose, Cook had saved his career.

"When you are playing for England, there's always pressure and when you don't perform that multiplies a lot. But to respond like I did today was very satisfying and showed some character," Cook said.

235* v Australia, Brisbane 2010

It was the Ashes, at the Gabba. England hadn't won an Ashes series down under since 1986/87. Add to that, England's record at the Gabba was disastrous. Despite Cook's 67 in the first innings, a Peter Siddle hat-trick had seen England collapse to 260 all out. Australia racked up 481 in response, and some feared an innings defeat for England. Instead, Cook dug himself in and scored a brilliant, unbeaten 235 to save the game. That knock laid the foundation for a very productive series for Cook, in which he scored a total of 766 runs, and was crucial to England winning their first away Ashes in over 30 years.

"I'm not great on cricketing history, but you'd be hard-pressed to think of a better innings in Australia," captain Andrew Strauss said of the knock.

176 v India, Ahmedabad 2012

Apart from Australia, India has been one of the most challenging countries for England. By this point, Strauss was no longer part of the side and Cook had taken over the reins of captaincy. In response to India's 521/8 declared, England had managed just 191 despite Cook's 41. Asked to follow-on, Cook showed his determination once again, hitting a brilliant 176. India won the game, but captain Cook had shown his side how it's done in India. England went on to win the four-Test series 2-1 and Cook again topped the batting charts, scoring a whopping 562 runs at 80.28.

95 v India, Southampton 2014

Captain Cook's form had dropped considerably - in nine innings prior to this knock, he had failed to get past 28. Even though he was captain, people were calling for his head. Once again with the odds against him and the pressure mounting, Cook produced a gritty knock. He fell five short of a century but backed it up with a 70 not out in the next innings, helping England to an easy victory. The knock ensured that the calls for Cook to be dropped were thwarted.

"I'd have loved that extra five runs. I have mixed feelings now. But if you had offered me 95 at the start of play, I would have bitten your hand off," Cook said of the knock, indicating the immense pressure he had been under.