Head coach Frank Lampard replaced Alonso with James, after the Spaniard’s poor first half display and the 19-year-old quickly stamped his authority on the game.
The Chelsea academy product went on to score a crucial goal that completed Chelsea’s comeback against nine-man Ajax.
Cole heaped praises on James after his introduction improved the Blues’ second half performance.
“When I was playing in America [with Tampa Bay Rowdies], I came around to train with the kids,” Cole told BT Sport of linking up with his former side during a pre-season training camp.
“We were having shooting session and the kids' shooting was erratic, but James was on the money, on the money, whipping crosses, it was like watching Beckham.”
Speaking after the game, the Englishman revealed what Lampard told him before coming on to replace Alonso.
"It was a crazy game.” James told reporters after the epic game.
“They were hard to break down and we took advantage of them going down to nine men, it was a shame we couldn't win. Scoring a goal is a bonus.”
“The manager told me to come on and liven the boys up, we had chances to win it but from where we were at half time it's a good result.”
“I had some mad night and some great nights, but for everything that it was, it was certainly right up there.”
“Chelsea fans know the story of what we have done in the Champions League but I don’t really want to talk about that.
“For a performance like today you need personalities and characters – at 4-1 down it is easy to give it away and give it up.”
James made history by becoming the youngest Chelsea scorer in the Champions League at the age 19 years, 332 days, beating Arjen Robben’s previous record of 20 years and 284 days.