Van Persie fires Arsenal into last 16

Robin van Persie scored twice as Arsenal booked their place in the Champions League knockout phase here on Wednesday with a 2-1 defeat of German champions Borussia Dortmund. Dutch international van Persie took his tally for the season to a remarkable 21 in all competitions with two second-half goals that ensured the Premier League side will finish Group F in top spot with one game left. Van Persie's double strike underscored the Arsenal captain's importance to the English club, who have gradually got their campaign back on track after a disastrous start to the campaign. Van Persie struck in the 49th and 86th minutes to finally snuff out the challenge of the Bundesliga representatives. Japan international Shinji Kagawa scored a late consolation for Dortmund in injury time but it was too little, too late as Arsenal reached the last 16 of the Champions League for the 12th straight year. Arsenal manager Arsene Wenger praised van Persie's match-winning contribution after the victory. "He's in a period where he doesn't have to look for goals -- they just come naturally for him. He's always in the right place at the right moment," Wenger said. Arsenal midfielder Alex Song said van Persie was in "unbelievable form". "He is very important and we hope he doesn't get injured because when he does, it is very difficult for us. We just need to keep him in good form," Song said. A disappointing first half saw neither side manage to take control of the contest, with Dortmund's feisty midfield tackling preventing Arsenal from establishing any sort of rhythm. Dortmund's hopes of victory were dealt a blow within the opening half an hour, however, when coach Jurgen Klopp was forced to re-shuffle his pack after two injury substitutions. Sven Bender was the first to exit, replaced by Moritz Leitner on 26 minutes after suffering a broken jaw in a collision with Thomas Vermaelen. Mario Goetze -- the 19-year-old wunderkind linked with a move to Arsenal -- was the next to depart, coming off for Ivan Perisic with what looked like a knee injury. Klopp later said the injuries disrupted his team's chances. "We lost our rhythm after the injuries," Klopp said. "It took us four or five minutes to find ourselves again. "The boys tried hard but we just played wildly. The result was deserved." Goetze had threatened to make a dramatic impact early on when he played in Robert Lewandowski in the first minute but Arsenal goalkeeper Wojciech Szczesny was alert to the threat and smothered the danger. At the other end, Arsenal chances were few and far between, with van Persie getting the home side's first attempt on goal with a tame header on 12 minutes that posed no threat to Dortmund's Roman Weidenfeller. Theo Walcott had the ball in the net on the 40-minute mark after receiving a neat pass from Aaron Ramsey, but the England winger was correctly adjudged offside. Another promising Arsenal attack came to nothing just before the break when Walcott's dangerous first-time cross into the box was palmed away by Weidenfeller. But the game came to life in the opening minutes of the second half, with Dortmund slicing open the Arsenal defence with a lovely passing move that ended with Szczesny saving smartly from Kagawa. Dortmund were made to pay for their profligacy shortly afterwards, when van Persie fired Arsenal into the lead. The Dutchman's goal owed everything to an improbable assist from Song, the Cameroon midfielder dribbling past three Dortmund defenders before crossing for van Persie to steer a downward header past Weidenfeller. The goal settled Arsenal and they could have been out of sight on 60 minutes when Gervinho was sent racing through on goal after a clever flick from Ramsey. The Ivorian rounded Weidenfeller but fatally took one touch too many and Felipe Santana was able to lunge in and clear to safety. With full-time looming, van Persie then made sure of the victory, sweeping home after Vermaelen's flick-on from Mikel Arteta's corner.