Nigeria striker Obafemi Martins left Inter Milan for Newcastle United on Thursday for a fee of 15 million euros ($19.24 million).
"He has always been my number one target but I didn't say that earlier because it alerts other clubs," Newcastle manager Glenn Roeder told the Premier League team's official website.
"We have had to be very patient and had to keep chipping away at Inter to buy their player."
Martins signed a five-year contract after agreeing personal terms and passing a medical.
He was introduced to the St James' Park crowd before Thursday's UEFA Cup second qualification round second leg against Latvia's FK Ventspils.
The game ended in a 0-0 draw, allowing Newcastle to reach the first round 1-0 on aggregate.
Newcastle have been desperate for a top-drawer striker. Alan Shearer has retired while England forward Michael Owen is not expected back until 2007 after his World Cup knee injury.
The 21-year-old Martins, who joined Inter in 2002, is a powerfully built forward who can run at defences.
In December last year he extended his Inter contract until 2010 but the close-season acquisitions of Argentina striker Hernan Crespo from Chelsea and Sweden frontman Zlatan Ibrahimovic from Juventus, in the wake of Italy's match-fixing scandal, have pushed him down the pecking order.
Martins comes from Lagos and made his way as a teenager to Reggiana in Italy without any time in formal football structures in Nigeria.
Roeder said he is keen to make more signings before the transfer window closed.
"Hopefully we can add another couple of players before Thursday's deadline and then I will have a squad to attack the first half of the season," he said.
"We haven't suddenly decided we want them. We've been working on them for weeks and we just need one or two things to happen to make it roll."
