Boro were delighted to land Turkey international Tuncay Sanli on a free transfer from Fenerbahce, subject to a medical, yesterday, and with chairman Steve Gibson hoping for "spectacular" captures to come, are said to be closing in on another unnamed striker.

The Teessiders have moved quickly to ease the disappointment of Mark Viduka's departure to Newcastle with some fans expressing disquiet, and Southgate is confident their patience will be rewarded.

He said: "It is really about making sure we are ready no matter what the opposition.

"I can assure our supporters we are working very hard behind the scenes at the moment to build the squad up and bring in new signings.

"I think there has been some concern among the supporters, but it is important to remember that it is not about the squad we have now in the middle of June, it is about the squad we will have when the season kicks off on August 11.

"I would just ask the fans to be patient, bear with us and trust us."

Tuncay's arrival, coupled with the arrangement with Arsenal for Jeremie Aliadiere and the pursuit of their mystery target, comes as speculation mounts over Ayegbeni Yakubu's future at the Riverside Stadium.

Boro have privately dismissed reports that Portsmouth have tabled a £12million bid for their former player, who left Fratton Park for the north-east in July 2005.

However, Harry Redknapp's interest is well known and having made a previous attempt to re-sign the Nigeria international, it would be no surprise if a bid did materialise.

Another transfer breakthrough would leave Boro with their latest target, Tuncay, Yakubu, Aliadiere and Dong-Gook Lee up front, and that could mean they would at least listen to a sizeable offer for their £7.5million signing.

Gibson revealed earlier this week the club is looking for one or preferably two strikers, two midfielders and a right-back, although they appear to have suffered a setback in their search for one of those midfielders.

After tying up the Tuncay deal in Istanbul, chief executive Keith Lamb stayed in Turkey to discuss a move for Trabzonspor's Gokdeniz Karadeniz.

However, it is understood he returned empty-handed after refusing to get involved in a bidding war as interest emerged from elsewhere, and it remains to be seen if the deal can be resurrected.

Meanwhile, Southgate has warned there will be no room for complacency at the Riverside after the fixture list handed them a promising start to the new campaign when it was published today.

Boro will entertain Blackburn on the opening day of the season with derby rivals Newcastle and Sunderland following Mark Hughes' men to Teesside within the first six weeks.

Southgate, whose side do not face any of last season's top four clubs until Chelsea visit the Riverside on October 20, said: "We have got to make sure we don't differentiate between the opposition teams like that because it doesn't usually work out the way you think it will.

"We had Reading on the opening day of last season and Portsmouth came to the Riverside early on.

"People might have thought those were comfortable games, but they were not and both teams went on to have excellent seasons, so you just never know.

"It's really about making sure we are ready no matter what the opposition."