Roberto Martínez declared his Wigan team are ready to do their own double by securing survival and winning silverware after they came from behind to defeat West Bromwich Albion, though the gloss was taken off a vital victory as wing-back Jean Beausejour was ruled out of the FA Cup final.

The 3-2 win moved Wigan to within two points of Sunderland, who play Stoke on Monday, and increased the pressure on Newcastle United, who drew 0-0 at West Ham. Newcastle are three points ahead of Wigan, having played a game more and with an inferior goal difference. "Jean is the negative," said Martínez. "He pulled his hamstring and it doesn't look great. These sort of injuries are usually 10 days."

Wigan may have to field a makeshift defence against Manchester City at Wembley on Saturday but their manager believes they were rewarded for focusing on attack at The Hawthorns. "It would have been a big mistake to try and sit back for a point," he said. "We had to win. We couldn't afford to hold on and take it to the next game."

Callum McManaman's 80th-minute decider means Wigan can move out of the relegation zone when they face Swansea on Tuesday but, when Albion led 1-0 and 2-1, Wigan were five points from safety with three games left.

"It was a performance full of character," Martínez added. "I couldn't be prouder of the players. I don't think many teams score three goals from open play against West Brom. Every other club fear to lose something. We don't. We don't fight to avoid relegation. It is not a negative, it is a positive. As a football club, we win the title every time we stay in the league. We have got a big-club mentality in those players. We are ready to win both trophies, the league and the FA Cup."

Wigan are seeking to ensure a ninth successive season of Premier League football but, although they are underdogs, Martínez insisted they are not reliant on luck. "We don't hope to get out. We know how to get out of the situation. Our players have the experience so that they are not going to get affected by the occasion."

Wigan have 35 points and Martínez, whose team face Swansea, Arsenal and Aston Villa, believes they could need another five to stay up. "I think the goal difference will have a say," he said. "It is going to be between 40 points and 39 points."