Brendan Rodgers insists he has been surprised by how well Celtic have done during his two seasons with the club.
The Bhoys beat Motherwell 2-0 in Saturday's Scottish Cup final as they completed an unprecedented second domestic clean sweep in a row.
Former Liverpool boss Rodgers is refusing to rest on his laurels though and is already keen to tie up the permanent transfer of Odsonne Edouard, who has been on loan at Celtic from Paris Saint-Germain this term.
"I need to push even harder now next year in relation to developing the players here first and foremost," he said. "And then bringing in players who can make a difference. It's a constant need to improve.
"We have a really young group that are improving and developing but to make a difference at that level [Europe] needs greater quality. We have to invest and improve. But the reality is that we can't spend fortunes because there's not masses of money there to do that."
Aberdeen finished second in the league this season but Rangers could be more of a threat in 2018/19 now that Steven Gerrard has taken over as the manager at Ibrox.
Rodgers is keen to play down the rivalry with the Gers though, adding: "Talk about Aberdeen. Aberdeen were second. Derek McInnes has done a brilliant job. Talk about them."
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