At the WACA ground today, Cook won his 100th Test cap against Australia in the third Ashes Test. The left-handed opener, who will turn 29 on Christmas Day, is now the youngest to 100-Test club.
The record was held by Tendulkar, who played his 100th Test at the age of 29 years and 134 days. The 40-year-old Tendulkar, who retired from international cricket last month, played the milestone Test against England in 2002 at The Oval in London.
Tendulkar holds the record for most number of Test appearances with 200 and is also the leading run scorer and most century maker in the five-day game.
In the same Test today, Australia skipper Michael Clarke too completed 100 Tests. This is the first instance in history that both captains have entered 100-Test club in same match.
Cook made his debut against India in Nagpur in 2006 and has so far scored 7,883 runs with 25 hundreds.
Many former cricketers are backing Cook to break Tendulkar's records in Tests.
Australia lead the five-match Ashes series 2-0.