Hartlepool United boss Darren Sarll admits he is still to be convinced by trialist defender Billy Sass-Davies

The 24-year-old, who has spent the last couple of weeks on trial at Pools, impressed supporters with an assured performance during Saturday's thumping win over South Shields.

However, the straight-talking Sarll, who is renowned for being demanding and difficult to please, hasn't been quite as enamoured as sections of the fanbase and suggested that Sass-Davies has been below the levels he expects.

Sarll knows Sass-Davies well, having signed him on loan for Yeovil, where the pair experienced the tragic suicide of Glovers skipper Lee Colins, and Woking.

Having progressed through the ranks at Crewe and represented Wales up to under-21 level, the defender's career has stalled somewhat and he endured an indifferent season on loan at Boreham Wood last term, making 36 appearances as the Hertfordshire outfit were relegated from the National League.

Having spent eight years with Crewe, during which time he played 42 games and was sent out on loan a staggering 10 times, he was released earlier this summer and is now on the hunt for a new club.

Given his relationship with Sarll, his National League experience, his solid showing at the weekend and Hartlepool's need for cover in defence, a move for Sass-Davies seemed like it made perfect sense.

While the move could well still materialise, Sarll admitted he still needs to be convinced that Sass-Davies can rise to the challenge.

"I'm really honest with Bill, I thought he was way below his level when he came here, way below," he told BBC Radio Tees Sport.

"I thought he was way below his level last year, I really did.

"I don't think he's maximised last season in any way, shape or form.

"This is nothing that I've not said to him, man to man.

"I think Billy has exceptional potential, but having potential and realising it are two different things.

"I've been a lot happier with Billy this week, in training he's been far, far better.

"I liked half an hour of his game on Saturday, which is the most I liked of anyone.

"I thought for half an hour we were very, very good but I thought the other 60 was meh. It was ok.

"I think his levels have gone up this week in training.

"These players, whether I've known them previously or whatever, they've got to impress us.

"They've got to impress me, I've got to want them. That's not always the easiest thing in the world to do.

"I do like what Bill's done this week. I think you'll only ever see a player at his best when physically he's at his best.

"I think Bill's probably 10 days, two weeks behind everyone physically.

"The last couple of days in training, he has stepped up, which he needed to, he did need to.

"He knows that what I've seen so far wasn't going to cut it."