Eleven changes were made to the starting line-up and although the goals mostly came from the more established players, with Ross Barkley and Michy Batshuayi finding the net early on with firm strikes, Pedro netting from the penalty spot and then Kurt Zouma poking in the fourth in the second half. Three players who started a Chelsea game for the first time all played their part.One of those, Reece James, rifled in our fifth goal and although Grimsby had scored in the first half to pull it back to 2-1 for a while, a comprehensive win was completed by Batshuayi drilling in his second of the night to make the score 6-1 and then the returning Callum Hudson-Odoi netting number seven.To add to the story, two further debutants who have come through our Academy were brought on in the second half.

In his starting line-up Frank Lampard handed debuts to James, who rewarded that choice by setting up two of the goals as well as scoring his one, and Marc Guehi in defence. There was also a first start to Billy Gilmour in midfield. Hudson-Odoi was able to make his comeback from the start after injury and played 90 minutes but it was not only Academy products selected.Experience was added by Willy Caballero in goal and Pedro playing in the no.10 role. The Spaniard was tonight’s skipper, and Barkley was alongside Gilmour in the engine room in the middle. Christian Pulisic was given his first start in four games and the Academy players blooded during the second half were Ian Maatsen and Tino Anjorin.

Other London clubs may have suffered against League Two opposition in the Carabao Cup this week but the gap between these two sides at Stamford Bridge was emphasised when it took just under four minutes for Barkley to give Chelsea the lead. It was a goal that was as simple as it was effective. Given the ball outside the area, the England international embarked on a run around the edge of the Grimsby defence which they proved powerless to stop. With the target now in front of him, Barkley smashed the ball past the exposed James McKeown and inside the near post.

Three minutes later it was 2-0 already, Batshuayi finding the net with a convincing strike after James had attacked down the right and picked the Belgian out in the centre. James had his first assist, Michy his 20th Chelsea goal.Alonso was the next to go for goal when he struck a 16th-minute free-kick over the bar but then the Mariners pulled a goal back with one of the best strikes of the night. Winger Matt Green was the scorer, latching onto a flick-on and firing the ball in just underneath Caballero’s crossbar.So no first clean sheet of the season tonight but it was soon back to Chelsea making the best chances and when Christian Pulisic’s speed off the mark earned his team a free-kick and the opposition’s scorer Green a booking, Pedro took the kick that a diving Batshuayi headed just wide.Pulisic tested the Grimsby defence with two dangerous deliveries from his position out on the right of the Chelsea team before with seven minutes to go to the break, Gilmour, who been tidy and frequently involved, played a great pass forward to Hudson-Odoi. On the left today and able to cut in and shot with his favourite foot, he did just that but saw his effort blocked.A Hudson-Odoi back-heel after he collected Pedro’s cross-field pass then set up Alonso to be the next to send the ball into the danger zone. Chelsea were looking good for a third goal before half-time and indeed we got it, from the penalty spot.

Kurt Zouma was hauled back as a corner came in. Green, who was certainly enjoying an eventful half, was the culprit. Barkley, who missed from the spot last week, was on the pitch but Pedro took on the penalty duty tonight and made no mistake. 3-1.

The first chance to make it 4-1 in the second half fell the way of Batshuayi who drilled wide and Grimsby could have conceded their second penalty at a corner but were fortunate the ref took a lenient view of a tug on Alonso.Instead the Blues scored from a free-kick routine, Zouma extending one of his long legs at the far post to direct in a James cross. The young right-back now had two assists to his name while for Zouma, it was his first goal since returning from loan on almost the fifth anniversary after his first for the club.One of James' fellow youth products, Hudson-Odoi, had one his deliveries clawed away from under the crossbar by the Grimsby keeper and with 66 minutes played, the debuts continued with Maatsen replacing Alonso at left-back and Anjorin on for Pedro in midfield. Both did their bit to threaten the Grimsby goal before the end.It was James, with a 20-yard curler on 82 minutes after Grimsby made a meal of clearing a corner, who was next to score to make it 5-1, and then Batshuayi scored a well-worked goal. There was still time for Hudson-Odoi to make his mark. It was shaping up to be a frustrating evening in front of goal for the 18-year-old who had two late one-on-ones saved but then he gave McKeown no chance at the near post with a fierce drive at the end of a run.

That was 7-1, and yet more justification for Lampard placing his faith in plenty of youth.Chelsea (4-2-3-1): Caballero; James, Guehi, Zouma, Alonso (Maatsen 66); Barkley, Gilmour; Hudson-Odoi, Pedro (c) (Anjorin 66), Pulisic, Batshuayi.Unused subs Cumming, Tomori, Jorginho, Mount, Abraham.Scorers Barkley 4, Bathsuayi 7, 86, Pedro 43 pen, Zouma 56, James 82, Hudson-Odoi 89

Grimsby (4-4-1-1): McKeown (c); Hendrie, Davis, Pollock Gibson (Cook 70); Hewitt, Clifton (Wright 56), Hessenthaler, Green (Ogbu 63); Whitehouse; Hanson.Unused subs Russell, Rose, Cardwell, Vernam.Scorer Green 19Booked Green 28

Crowd 39,674Referee Keith Stroud