Aston Villa boss Martin O'Neill admits strengthening his defence is now a market priority.

"We need to strengthen defensively first of all. At the moment, if players stay fit, we have enough options from an attacking perspective," he told Villa's website.

"That doesn't mean we can't add to that - we can do. But defensively we need to get some players. I want to try to get value - I don't work on the assumption if I can bring six players in and three of them work, then that's good.

"I want everything to work if it's all possible. That might not materialise, but it's how I've always worked. I'll know the players - whichever players arrive here, it won't be somebody I'll take a chance on.

"You take a chance on every player if the fee is relatively high and nothing is ever guaranteed in this game, but I'll have done as much homework as I possibly can before they come in.

"It would be nice to do every type of assessment on a player, but it doesn't always materialise.

"You don't really know players until you have signed them and work with them, but you try to do as much work on them beforehand, and that's what I'll do."

O'Neill continued: "Perhaps this season, outside of Liverpool and Manchester United, football clubs do not have limitless amounts of money.

"So we have to try to prioritise and value for money is what we have to try to look for in these days of inflated prices.

"I've said we want to strengthen the squad because I don't want to be in a position where we were in November ad December when we were desperate for January to arrive so we could strengthen.

"And even when it does arrive, it doesn't arrive on January 1 or 2 - it doesn't work like that. We were left with the smallest squad in the league and the results went accordingly.

"So I don't want to be in that position again. We might be, but I'm hoping it's not through strength in depth.

"I want players who are willing to fight for their places - Marlon could have gone elsewhere and be guaranteed a first team place at least for a while, although nothing is ever guaranteed.

"But he chose to come here and battle when he knows he's not certain of a place. That's very encouraging - it's what I want and it's what I need.

"I want a bit of competition and I don't think we ever had up until the back end of last season when we were playing well and everyone wanted to play."