Arsenal manager Unai Emery has defended his decision to substitute Alexandre Lacazette late on against Fulham, which was met with boos from the home crowd.The Gunners secured a 4-1 win over the Cottagers at Emirates Stadium on Tuesday afternoon, thanks to goals from Granit Xhaka, Lacazette, Aaron Ramsey and Pierre-Emerick Aubameyang.The French striker was lively throughout and managed to add to his goal tally for the season with a cool finish on 55 minutes, after a typically flowing move. Article continues below Editors’ Picks ‘There is no creativity’ – Can Solskjaer get Man Utd scoring freely again? ‘Everyone legged it on to the pitch!’ – How Foden went from Man City superfan to future superstar Emery out of jail – for now – as brilliant Pepe papers over Arsenal’s cracks What is Manchester United’s ownership situation and how would Kevin Glazer’s sale of shares affect the club? Emery replaced Lacazette with Ramsey with 15 minutes to go and the switch ultimately paid dividends, as Arsenal added two more goals to add gloss to the final scoreline.The Spanish boss was berated by fans after initially making the substitution and while he acknowledged that the supporters have every right to voice their opinion, he felt that his decision was in the best interests of the team.”I understand the supporters,” Emery said post-match. “I need to do my work. Tactically we thought at that moment we needed to change for more balance”Above all we knew that [Jean Michael] Seri was coming on and we needed a player close to him, not to let him play easily with the ball. Ramsey can do that and also help us in the attack, and he scored”In my career, I have different moments when I made similar decisions. We need to decide with a cold mind what is the best decision.”Arsenal remain fifth in the Premier League after their latest victory, two points behind fourth-placed Chelsea having played a game more.December proved to be a difficult month for the Gunners, as they only managed to pick up three wins from seven top-flight matches, which has left them facing a tough task to qualify for next year’s Champions League.An FA Cup third round clash against Blackpool now awaits Emery’s side on Saturday, before a return to Premier League action the following weekend against West Ham.