MANCHESTER, England -- Frank Lampard has hit back at Jose Mourinho's criticism of his team selection against Manchester United by insisting that he doesn't care what pundits say.

Mourinho, working for Sky Sports, said Lampard could have picked a team with more "know how" instead of selecting youngsters Mason Mount and Tammy Abraham for the 4-0 defeat at Old Trafford.

But Lampard rejected his former manager's claim by insisting more experienced players like N'Golo Kante, Olivier Giroud and Willian were not available to start.

"I can't drag people out of the medical room, whether they're experienced or not," said Lampard after his first competitive game as Chelsea boss.

"The players we played today, and on the bench, are the players we have. We were clearly the better team for 45 or even 60 minutes but we made individual errors that led to four goals from five shots. That's the harsh reality.

"I don't have to be too concerned about what anyone else says -- the pundits -- but what is clear is the squad is the squad we've got and I believe in it.

"Had we gone in at half-time 2-1 or 3-1 up, which we should have done, the game would have been completely different."

Lampard's team hit the post twice during an impressive first-half display but went in at the break a goal down thanks to Marcus Rashford's 18th-minute penalty.

United were clinical after the break and scored three times in 16 minutes through Rashford, Anthony Martial and Dan James prompting Mourinho, who also said Man City's "B Team" could beat United, to suggest that Chelsea had been hurt by a lack of experience.

"My feeling is that today they had a possibility to play with more know-how," Mourinho said. "[Marcos] Alonso was on the bench, Kante was on the bench, Giroud was on the bench, and to come to Old Trafford, even if this is not the huge Manchester United that used to scare people, it's Manchester United.

"It's the first match at home, the first match of the season, people are excited, the stadium is on fire waiting for something positive.

"A little bit of experience [from Chelsea] would fit well with the team. You look to the performance of Mason Mount, the performance of Tammy Abraham, you look to the performance even of [Andreas] Christensen and for matches of this dimension you need a little bit more."

Lampard admitted that the match had been a "reality check" for his young team, but refused to make excuses over missing international stars as the reason for the result.

"We are missing internationals and big players but I don't want that excuse," said Lampard.

"The team we put out today was clearly competing in the game for long periods but we made four mistakes and they were clinical in the way they put them away. There's a reality check for us all."

Abraham and Emerson struck the frame of the goal before half-time and Chelsea played some attractive football until United's powerful counter-attacking play exposed the away side's defensive weaknesses.

"They are a counter-attacking team, it's a big strength, they have pace and if you turn over the ball or give them opportunities they will counter," said Lampard.

"For massive parts of the game we didn't allow them to do that. We were the ones winning the ball back, but our final ball wasn't great. We were so comfortable in the first half, so loads of lessons for us.

"We can't make unforced errors and mistakes at this level. At the same time, it was nowhere near a 4-0."

Lampard was reluctant to dwell on the positives for his team but was justified in his view that the scoreline did not reflect his team's performance with the ball.

"Four mistakes for the goals, but we controlled major parts of the first half. We hit the woodwork, poor decisions in the final third when we should be able to get shots away, we should be in the lead at half-time," he said.

"Early in the second half I didn't mind it -- and then two mistakes for their second and third goals -- it's much easier for them to play at 3-0 up. At 1-0, we were the better team, but I can't stand here and look happy with that."

Information from Reuters was used in this story.