Billy Gilmour, making his first start, was a stand-out performer in midfield and fellow rookies James and Marc Guehi also impressed.

Once Zouma tapped in the fourth, from a fine cross from James on 11 minutes,  into the second half, Lampard threw on two more debutants, Tino Anjorin and Ian Maatsen, meaning the Blues finished the night with six academy graduates on the pitch.

Lampard said: "It was pleasing on a lot of levels. It was not complete. But I'm pleased some players who have not been playing so many minutes played, some debuts, and the young lads who came on improved the team which was nice. It's nice to get that first home win.

"I thought Gilmour ran the game from midfield, and Guehi was solid.  They've been outstanding this year.

"With his end product Reece showed what he can do, an assist and a goal, but Reece's performances on loan last year at Wigan showed the talent he's got.

"I think he's going to be a big player for this club. It's just the start for Reece.

"And the young subs showed how comfortable they are on the ball. Now the hard work starts to get in the team regularly.

"It says a lot about the academy, and nights like this give the opportunity to mix the team up and give them a chance, it gives good recognition to the academy."

Grimsby, to their credit, gave Chelsea a minor fright when, at 2-0 down, veteran Matt Green scored the goal of the night with a sublime volley.

But when Green hauled down Zouma and Pedro rolled in the spot-kick just before half-time, any hopes of a repeat of Colchester's win over Tottenham 24 hours earlier disappeared.

Barkley had been Lampard's designated penalty-taker against Valencia and had vowed to continue after his miss a fortnight ago.

But Lampard cleared up any confusion, adding: "The good thing in this job is I can choose who does what! I chose Pedro to be captain and take the penalties tonight."

The Blues were handed a visit from Manchester United in the fourth round.

Mariners manager Michael Jolley was quoted in the Grimsby Telegraph saying: "The result does sting a little bit, you never want to get beat as a professional by that scoreline.

"But I think we've got to keep it in some context, we played against an absolutely top outfit tonight, and the quality of their players is unbelievable."