Wayne Rooney thinks Danny Welbeck did the right thing by leaving Manchester United for Arsenal this summer.
Many United fans were shocked earlier this year when Louis van Gaal sanctioned Welbeck's £16million transfer to the north London club.
Welbeck is a life-long United fan and joined the club as an eight-year-old having grown up in the Longsight area of Manchester, which is just four miles away from Old Trafford.
During his 11-year spell at United, Rooney watched the pacy forward progress from teenage prodigy to first-team striker and admits it will be strange to play against the 23-year-old striker when the Red Devils travel to the Emirates Stadium on Saturday.
Manchester United injury list
Manchester United injury list
1/5 Wayne Rooney
There is uncertainty over the extent of the Manchester United captain's injury, with fears he may have suffered ligament damage to his knee during the 3-0 defeat to Everton. Unlikely to feature against West Brom and could miss the rest of the season.
2/5 Michael Carrick
Having limped off in the 4-2 derby victory over Manchester City, it's uncertain if the England midfielder will fit for this weekend. Was unable to even make the bench for the defeat to Everton.
The right-back's return to action has suffered a set-back. After making a short appearance in the 3-0 win over Tottenham in March, the Brazilian has been pushing for full fitness. However he suffered a blow to the ribs in an Under-21 match against Leicester and could miss the rest of the season.
4/5 Marcos Rojo
Having missed the games against Chelsea and Everton due to a groin injury, the Argentina international is pushing for a return and could feature this weekend.
5/5 Phil Jones
Fellow defender Phil Jones also missed the defeats to Chelsea and Evertton but the England international has returned to training after a foot complaint and could play at against West Brom.
"Of course, Danny has been here all of his life," Rooney told MUTV. "He is a Manchester lad so it is weird seeing him [there].
"But that's football nowadays and players move on."
Welbeck started the vast majority of games on United's successful tour of the United States, however he struggled to get in the starting line-up soon after the season began, with Van Gaal claiming his goal-scoring record was not good enough.
Welbeck scored 29 times in 142 United appearances, but since his move he has found the net on 10 occasions for club and country.
Rooney, who played alongside Welbeck for England against Slovenia and Scotland in the recent international break, thinks leaving United has been beneficial for his former team-mate.
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"I think, for Danny, and for his own personal career, it was probably the best move for him," Rooney said.
"He's done great and scored a few goals and is playing well. Danny gives you what he always gives you - a good shift. He works hard for the team.
"At times, as I said to him, he works a bit too hard but he's scoring goals and he's doing well."
Arsenal against United has been one of the biggest fixtures on the calendar in recent years, but neither side is considered a serious title contender this season.
For Rooney, the fixture still brings back fond memories, though.
"We've had some great memories," the England captain added.
"Beating them in the Champions League semi-final (in 2009) was probably the highlight."
The same fixture last year ended in a dull 0-0 draw, but given the poor defensive record of both teams, it is unlikely the scoreline will be the same this season.
Rooney is hoping United can strike early against their opponents and is expecting a tough match.
"It's always a tight game and whoever gets the first goal normally wins or gets a result," the 29-year-old said.
"We have to go there with a good team shape and a good unit to make sure we do everything right.
"Arsenal have got a good squad, an exciting squad with a lot of young players and a lot of English players which is great for England. We know they play with a lot of energy and we'll have to be at our best to beat them."
Van Gaal has been hit by an injury crisis on the eve of the match.
Radamel Falcao, Daley Blind, Jonny Evans, Phil Jones, Marcos Rojo and Rafael are all out so Chris Smalling is likely to be partnered at centre-back by teenager Paddy McNair.
Fitness tests will be given to Michael Carrick, Luke Shaw, David de Gea and Angel di Maria, who all suffered minor injuries on international duty.