The feelgood factor at Ajax created by back-to-back wins has evaporated after two key players returned from the international break with injuries.
After a Champions League victory over Celtic and a 3-0 beating of NEC Nijmegen in the Eredivisie, the Amsterdammers appeared to have finally found some consistency after an up-and-down period.
But coach Frank de Boer wore a gloomy look when he assessed the state of his squad ahead of Saturday's clash with Heracles at the ArenA.
Striker Kolbeinn Sigthorsson and attacking midfielder Siem de Jong will miss out this weekend and are also doubtful for key European assignments against Barcelona and AC Milan.
Sigthorsson sustained an ankle injury in Iceland's World Cup play-off defeat to Croatia while De Jong suffered a hamstring strain in Holland's friendly draw with Colombia.
"They will both go for a scan," De Boer said. "But we already know we will miss them.
"And that's a real downer."
As for his options, De Boer told De Telegraaf newspaper: "Danny Hoesen could start but Davy Klaassen can also fill the role.
"Bojan Krkic is another option but the Heracles and Barcelona matches are likely to come too soon."
Ajax head into round 14 in third place, just behind AZ Alkmaar and two points adrift of surprise leaders Vitesse Arnhem.
Vitesse have won four of their last five games in league and cup and will expect to improve that record on Sunday at Go Ahead Eagles.
AZ host Roda JC looking to get back to winning ways following a 2-2 draw with Feyenoord last time out.
The Rotterdammers go to RKC Waalwijk having this week played down talk of re-signing former striker John Guidetti.
Guidetti is reportedly available for transfer from Manchester City in January with the speculation prompting a Feyenoord fans' group to start collecting money to try to bring the Swede back to De Kuip.
The 21-year-old grabbed 20 goals in 23 games in a hugely-successful loan spell in the 2011-12 season but club chief executive Eric Gudde has played down talk of a fan-backed return.
He said on the club's website: "We have nothing but praise for the good intentions of our supporters that they should start a collection to force his return as soon as possible.
"It shows their love for both Feyenoord and John. But no matter how well intended, attracting a player through donations is not the way.
"Quite apart from the legal and tax aspects, we can only buy a player for any transfer fee if his salary falls in line with our policies."
PSV Eindhoven also have striker issues to contend with.
Sweden international Ola Toivonen is out of contract at the end of the season and has made it clear he would like to leave the Philips Stadion in January.
PSV technical director Marcel Brands told De Telegraaf: "That does not surprise me because if Ola hadn't had doubts (about re-signing) he would have done so in August.
"Apparently (a January move) is Ola's wish but it is impossible to say if that's the best scenario for PSV.
"Our first scenario is a contract extension. Also we have not had any contact with a club regarding a move in January."
Eighth-placed PSV take on Heerenveen on Saturday.
Elsewhere, rock-bottom NEC go to Cambuur while, on Sunday, fourth-placed FC Groningen host PEC Zwolle, NAC Breda go to FC Twente and FC Utrecht meet ADO Den Haag.