West Ham manager Sam Allardyce believes he is "one player of top quality" away from building a squad to take his side to the "next level" in the Premier League.
The Hammers secured a tenth-place finish on their return to the top flight last season, yet Allardyce is targeting even more now that his side have kick-started their pre-season preparations.
"What I want in that one player is top quality, I want that player coming in to challenge the players already here for their place immediately," Allardyce told West Ham's official website.
"I want somebody to come in and make a real difference, as we did last year when the players we brought in made a massive difference. That took us to the next level and led to us having a fantastic season and finishing tenth.
"You always want a little bit more and you are never satisfied as a manager. I am not saying that is the end of what we are going to bring in and we will look to add one more player at least."
Allardyce has hailed the summer signings of Andy Carroll, Romania captain Razvan Rat and Spanish goalkeeper Adrian and he believes his third season as West Ham boss has the potential to be the best yet.
"For me, it's two years in and fewer players will have to leave or come into the club, which is great for me," Allardyce added. "The last two seasons have been traumatic in change-around terms, particularly the first one when I look back on it.
"It was horrendous, with something like 28 players going out and 20 coming in during one season. We had to cope with that and re-build the football team.
"At this moment in time, I'm a lot more comfortable because the players and staff know what I am looking for and how I work. They know what I want and it is their responsibility to drive the players forward in every department to extract even more out of them this year than they did last season."