Barcelona will make a renewed effort to sign Cesc Fabregas this week, with a second bid being prepared of around £35m.
Arsenal have already rejected a £27m offer for their captain but the European champions will make one final attempt to conclude their three-year pursuit of the Spain international.
Negotiations between the two clubs are on-going as Barcelona continue their pre-season tour of the U.S., with manager Pep Guardiola clarifying he views Fabregas as the missing link in his current squad.
Guardiola told the Daily Telegraph: "We're short of just one player and everyone knows which one that is."
But manager Arsene Wenger remains adamant Fabregas will not be sold for less than £40m and it is far from certain the club will accept any new offer from Barcelona that falls short of their valuation.
Fabregas has missed all of Arsenal's pre-season matches this summer, with reports blaming a recurrent hamstring injury as well as the 24-year-old's "unsettled" mental state.
Wenger faces a further headache tomorrow at the club's annual member's day. Next season's team photograph is scheduled for Thursday and the club are believed to be considering taking two photos - with and without Fabregas - to avoid any embarrassment if the midfielder is subsequently sold to Barcelona.
The continuing uncertainty over Fabregas's future is threatening to undermine Arsenal's pursuit of Valencia forward Juan Mata, after the Gunners missed out on the 1 August deadline for triggering the player's £18m release clause.
The club are expected to make an improved offer for the Spain international but Valencia are now in a position to refuse to sell to any club who do not meet their own buy-out clause, believed to be in the region of £52m.
The midfielder's father and agent, Juan Manuel Mata Rodriguez, revealed that Valencia turned down a £14m bid from Arsenal on Monday.
"After some hesitation they answered 'no' to the offer," he said.
"My son remains a Valencia player, for now, but I don't think it's Arsenal's last offer. I think that Arsenal will come forward again. The situation is still evolving."
Wenger is reluctant to spend significant transfer funds until the situation with Fabregas is resolved. But the Arsenal manager finds himself under pressure even before the season starts, after fans booed the team off the field following last week's Emirates Cup.
The Gunners also face competition from Tottenham and Inter Milan for Mata. Rodriguez told reporters, "Are Inter Milan one of the interested teams? I know my son holds Milan in high esteem."
Meanwhile, Arsenal are weighing up a £10m bid for Birminhgam defender Scott Dann after becoming frustrated in their attempts to sign Blackburn's Chris Samba and Everton defender Phil Jagielka.
Wenger is reluctant to meet Everton's £18m valuation of Jagielka and has since turned his attention to Dann, 24, who impressed club scouts against Derby on Saturday.
Finally, Arsenal have reopened negociations over the signing of Costa Rican forward Joel Campbell from Deportivo Saprissa.
Campbell told crunchsports.com, "We are talking to Arsenal again. I have not signed yet, but I'm waiting to hear from my agents."