BBC reported that Chelsea had contacted Portugal Sports team for striker Hader and asked Bayern to make a permanent transfer offer for Jackson.

On Saturday, after Drapp Jr. suffered a hamstring injury, Chelsea withdrew permission to allow 24-year-old Jackson to go to Bayern for a medical examination. Previously, the two parties had reached a lease agreement with an initial fee of £13 million. At the same time, Chelsea also contacted Hader and Portuguese Sports to test potential transfer possibilities.

Jackson remained in Germany on Sunday and was desperate to leave Stamford Bridge. But as the situation changes, Chelsea is asking Bayern to renegotiate a permanent transfer agreement to fund the team's introduction of new strikers.

Of the three potential options, signing Hader and selling Jackson is the first choice, and coach Maresca is worried that Drapp Jr. will be injured and missed six to eight weeks. Any transaction depends on two points: one is that the two sides reached an agreement on the transfer fee, and the other is to persuade the 20-year-old international who has only played once for the Denmark national team to join Chelsea and compete with the other two strikers in the team.

Another option is Chelsea recalling Marc Guiu, who is on loan from Sunderland, but this requires an agreement between the two clubs.

In addition, Chelsea may also ask Jackson to return to London.

Chelsea had made an offer to Barcelona player Felmin on Saturday before Drapp Jr. was injured. In addition, Chelsea has a key priority: clearing out the last few "edge players" on the team, including Sterling, Chilville, DiSassi and Forfana.