Philip Cocu has had a relatively good start to his Derby career but there is still some doubt about whether he knows his best team, or who his main striker should be.

The Rams have struggled for goals from their front men a bit so far, although Martyn Waghorn's brace against Stoke at the weekend will have filled Cocu with some belief - despite him missing a one-on-one to secure all three points.

Along with Waghorn, the former PSV boss also has Mason Bennett and Jack Marriott to choose from, both of whom featured regularly under Frank Lampard, and along with Waghorn were rotated often last season.

So far, though, it is Waghorn who has been preferred, but his return of two goals in four games - including a penalty miss - may lead his manager to seek an alternative.

After the match against Bristol City, that could become more likely.

Waghorn linked play effectively enough but failed to show any real quality in the opposition final third and lacked the cutting edge which Derby needed, which was partly why they found themselves 2-0 down at half-time.

It was much the same after the break too until the introduction of Marriott in the 68th minute, who in the 85th minute instinctively turned in the box and curled a beautiful shot into the far corner using his weaker foot.

Marriott, unlike Waghorn or Bennett, is a natural goalscorer. He plays on impulse and is the poacher Derby need at this stage of the season.

Like in the play-off final last season, his impact off the bench was significant, and it can surely only be a matter of time before he gets a regular run in the starting XI.

With Tom Lawrence and Kieran Dowell operating in midfield Derby will create a lot of chances this season, particularly as they get more used to Cocu's playing style and if they get to play with the same striker week-in week-out.

It is difficult for them to get used to the differing playing styles of Waghorn and Marriott, with the latter preferring to run in behind in order to stretch defences, and Waghorn better suited with the ball to feet.

Waghorn's style may make him more suited to Cocu's tactics, as he will be better at retaining possession and better at bringing his teammates into play, but Marriott is more suited to the Championship.

He is also what Derby will need in most of the games they play as they will often need to break teams down, and against stubborn defences which may only give away one or two chances per match Marriott is the most likely of any Rams player to put those chances away.

Therefore, Cocu must adapt his style to get the best out of Marriott, and if he does so the goals he will score will surely be invaluable to Derby across the season.