ARSENAL are putting the finishing touches to the signing of Villarreal's Gabriel Paulista after the Brazilian defender was granted a work permit.

Gabriel has received formal approval from the Home Office and will undergo a medical at Arsenal's London Colney training ground on Monday while waiting for a visa application to be processed.

There were concerns Gabriel might not secure a work permit given he is uncapped for Brazil and rules state a player must have played in 75 per cent of his national team's matches in the last two years.

The Gunners, however, successfully argued the 24-year-old is an exceptional talent who will benefit the top level of English football.

The athletic centre-back will boost Arsene Wenger's defensive options, which have often been stretched this season due to injuries.

Villarreal announced on Saturday that Arsenal striker Joel Campbell would move to the Yellow Submarines on loan until the end of the season as part of the deal.

Campbell impressed while playing for Costa Rica at last summer's World Cup but the 22-year-old is yet to start a Barclays Premier League match for the Gunners this season

Meanwhile, Theo Walcott claims the return of Arsenal's injured stars has given the Gunners belief they can challenge for any trophy this season.

Walcott and Mesut Ozil have started less than 10 Premier League games between them in the current campaign but the pair were both on target as Arsenal edged into the FA Cup fifth round with a 3-2 win over Brighton on Sunday.

Walcott's goal was his first since New Year's Day 2014, with the winger enduring a 12-month absence with a cruciate ligament injury, while Ozil has had a knee problem and was making his first start since October.

The duo's recovery is a timely boost for the Gunners, who have also been strengthened by the returns of Olivier Giroud, Laurent Koscielny and Aaron Ramsey in recent weeks.

"It's like having new signings in the dressing room," Walcott said.

"Having the likes of Mesut back, getting a goal and playing very, very well - the chances will come to get games.

"There is competition for places now and it's going to be a headache for the manager to pick his best 11.

"Those players who have come back have done very well and it just shows we've got a great squad when everyone's completely fit.

"I think we can compete for anything this season now."

Arsenal play Monaco in the last 16 of the Champions League later this month but are currently fifth in the league, 13 points behind leaders Chelsea.

The Gunners' best chance of silverware appears to be retaining the FA Cup after a weekend of shocks saw Manchester City, Chelsea, Tottenham and Southampton all exit the competition in the fourth round.

"We've got to believe that this is a great opportunity and we want to hold on to the cup," Walcott said.

"It's our cup and it's a massive opportunity looking at all of those teams that haven't gone through.

"It depends on the draw but we believe that with the team that we've got and the players coming back to fitness, we can beat anyone."

Tomas Rosicky's superb volley ensured Arsenal held off a second-half fightback from Brighton, who twice reduced the deficit thanks to goals from Chris O'Grady and Sam Baldock.

After an excellent first-half display, the Gunners were left hanging on at the end and Walcott admits the team were just pleased to be through.

"That's what the FA Cup's about," Walcott added.

"You have to give credit to Brighton, they did very well and we did very well in places. It was a typical FA Cup tie.

"It was always going to be tough given the results that happened on Saturday so the most important thing is to go through - we did that and we're into the next round."