Antoine Griezmann should leave Atletico Madrid if he is not fully committed to the club, midfielder Koke has suggested.
The France star has agreed in principle to join Barcelona next year in a deal worth up to EUR90million, according to reports in his homeland.
Griezmann was heavily linked with Manchester United in the most recent transfer window but admitted it would feel like a betrayal to leave Atletico while they were unable to sign a replacement due to a FIFA-imposed transfer ban.
However, the rumours of Barca's approach combined with a poor run of form - he has scored just twice in LaLiga this season - has fuelled speculation that this will be his last campaign with Diego Simeone's side.
Koke insists his team-mate is as dedicated to Atletico as ever but says the club can do without players who no longer wish to be there.
"It's true that, during the last month, we haven't been at our best level. There have been good things and not so good things," he said.
"On Griezmann, he could have gone this summer and he didn't. I think he's happy.
"We always say that the person who isn't comfortable here says it, and they go. The club wants the best and people who are committed.
"Whoever isn't already [committed] knows what he has to do: to ask to leave, and leave. We want people at 100 per cent.
"He does look committed to Atletico. In the last month, the reality is that we haven't been any good and little by little we will improve."
Atletico face champions Real Madrid in the derby on Saturday, with both sides knowing a win could be vital to their hopes of hauling in league leaders Barcelona, who are four points clear of second-place Valencia.
Madrid have lost back-to-back away games against Girona and Tottenham but Koke does not expect that run to last.
"We haven't seen their best version yet but they have amazing players and always give their best," he said.
"[I expect] a Madrid who will give everything and come to the Wanda Metropolitano with a lot of desire.
"Every game against Real Madrid is special. The essence of a derby, even when you've played in a lot of them, is never lost."