Renshaw burst onto the swimming scene as the youngest member of last year's British team in Shanghai at the World Championships at the tender age of 15.
And, while that trip to China was more of a learning curve for the breaststroke specialist, what followed at the British trials in March of this year was quite remarkable.
Renshaw finished second in the 200m breaststroke final to Stacey Tadd but missed out on securing a spot at this summer's Olympics by less than a second.
Her final opportunity to swim under the FINA A time will come at the ASA National Championships in Sheffield and Cook is confident she will seal her spot at the second time of asking.
"There's no doubt in my mind that Molly will put right what she got wrong in the trials and go under the time she needs to," said Cook, who won 100m and 20m breaststroke gold at the 2006 Commonwealth Games in Melbourne.
"She knows this is her last chance so it's a case of looking at the trials and what went wrong and then just making a little tweak here or there.
"It can be a little bit annoying for the shorter distance swimmers, the sprinters if you like, because they have to alter their training schedule.
"But Molly will be fine and I'm confident that come the day she will secure her spot at the Olympics."
And, if Renshaw does manage to dip under the qualifying time and secure her spot, then Cook is adamant Renshaw has what it takes to upset the apple cart against the sports' biggest names this summer.
"These Olympics will be a big occasion for everyone, they don't get more important so in the nicest possible sense naivety will be a big help for Molly," he added.
"She knows she can swim at that level and I was so impressed with her performance at the trials, she looked so strong.
"I'm not talking about her race times or anything like that, I mean just pure racing ability and the way she went about the competition in the pool."