Manchester United’s opening bid for numero uno summer target Jadon Sancho has been rejected by Borussia Dortmund, according to reports.The Red Devils had been monitoring the Englishman for long, and Ole Gunnar Solskjaer is believed to be a huge admirer of the player. The Norwegian was hopeful to unleash an attacking trio of Marcus Rashford, Anthony Martial and Sancho this season, knowing very well that it would make Manchester United a force to reckon with.The right-wing has been Manchester United’s bane in recent years. A lot of players have tried and failed to own the position in the last few seasons. Solskjaer has used Juan Mata, Jesse Lingard and Daniel James on the right-wing, but none of them truly impressed in the long run.Mason Greenwood has come in and looked sharp, but the Norwegian would be wary of piling the pressure on an 18-year-old. Sancho’s arrival, as such, would have solved a long standing problem and added some serious firepower to an already impressive attack.Manchester United offered Dortmund €80m plus €20m for Jadon SanchoDespite their clear interest in the Englishman, Manchester United have been painfully slow in their approach to seal a deal for the player.The Red Devils brushed aside the August 10 deadline set by Dortmund, preferring to take their own sweet time to negotiate personal terms with the player.Once recent reports suggested that player wages and agent fees had been sorted, it was only a matter of time before the Red Devils began testing Dortmund’s resolve. And now, reports claim that the holy hour has arrived.Sky DE: Borussia Dortmund rejects €80m plus €20m addon bid for Jadon Sancho. Dortmund tells Man Utd the player is not for sale. #BVB #MUFC— Chris Williams (@Chris78Williams) September 29, 2020Manchester United have placed an opening offer of €80m, with a further €20m in add ons, for Jadon Sancho.However, the stunning €100m offer is still a little short of Dortmund's €108m valuation of the player, and as such, the Bundesliga side have rejected the offer. In addition, Dortmund have also informed the Red Devils that the player will not be sold this summer.Jadon Sancho has not travelled with Borussia Dortmund to take part in the German Super Cup tie against Bayen Munich. However, that is because he is suffering from a respiratory infection although his COVID-19 test results came out negative.During last contacts, Borussia Dortmund told again to Man United they won’t accept any bid for less than €120m for Sancho. Still same position - #MUFC were ready to make a new bid around €90m but it would be refused. BVB are still convinced to keep Sancho this season 🔴 #Sancho— Fabrizio Romano (@FabrizioRomano) September 29, 2020With less than a week remaining before the close of the transfer window, Manchester United are running out of time to play the waiting game on Jadon Sancho.Would the Red Devils match Dortmund’s valuation of the player and force the Bundesliga side to come to a decision? Having come so far, Manchester United might be tempted to coax Dortmund into submission. However, only time will tell if they will be successful.Also Read: Marco Reus provides an interesting update about Manchester United target Jadon Sancho’s future