PAUL Clement was left frustrated by the lack of impact from his substitutes, as Reading suffered a last-gasp defeat (2-1) to Derby County in their opening match of the season.

Royals led after 52 minutes through Jon Dadi Bodvarsson's header, but a second-half comeback earned Frank Lampard a 94th minute winner on his managerial debut.

The equaliser came through Mason Mount, who managed to beat Vito Mannone with a hopeful left-footed strike from outside the box.

The home side lost their cutting edge from the first half and were made to rue several missed opportunities when Tom Lawrence guided a header over Mannone in the dying seconds.

Clement said: "Clearly if you lose the game with the last kick it is tough. Particularly the first game of the season.

"We have just got to make sure we don't lose it. It was a fantastic cross and header.

"We did well in the first half. Our shape was fantastic. Derby changed their style in the second half and spaces opened up as players tired.

"It is a harsh result and a big lesson for us so early in the season. Our goal was a great goal.

"The first [Derby] goal was soft on our part, but then Vito made a wonderful save later on."

Icelandic striker Bodvarsson was guilty of squandering a couple of chances in the first half, but made amends when he latched onto Mo Barrow's looping cross from the left wing.

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Sam Baldock and Yakou Meite were introduced, but Clement believes his substitutes did not make the same impact as Derby's.

It was the telling cross of substitute Mason Bennett that allowed Lawrence the space to work an angle at goal and his header ensured Reading started the season with defeat after he had an early effort ruled out for offside.

Clement added: "I was pleased with our performance in the first half. Their changes worked better than our changes.

"We didn't gain anything from our changes. The players really need to come on and do a job."

The Royals boss did not rule out the possibility of making further changes before the end of the transfer window and said the future of Liam Moore remained unclear after the defender handed in a transfer request.

He said: "We have to be ready to do something.

"We are still in the market to do a couple of things before the end of the loan window.

"Nothing has changed [with Moore] since the last time.

"I would never make a judgement based on just one game."