The Dutch winger will make his Boro debut this afternoon following his loan move from Huddersfield Town, his first competitive appearance since lining up for the Terriers in the 1-1 draw at Burnley on October 6.
The 27-year-old will bring badly-needed pace and width to Boro’s attack, with manager Tony Pulis also keen to supplement his arrival with further additions.
But given van la Parra’s lack of recent game time, the Boro chief says that some patience will be required before the winger gets fully up to speed.
Pulis said: “He has not played much football, but we need to get him fit.
“He will start. He has got what we need with that pace and he is a ‘leg-beater’ who can take people out of the game.
“But we are going to have to be a little bit patient with him because of his fitness levels and, speaking to the medical people, he will not be fit enough to play for 90 minutes.”
Middlesbrough are set to field a makeshift backline with Aden Flint, Daniel Ayala and Ryan Shotton out.
Highly-rated young defender Nathan Wood – who became Boro’s youngest player when he lined up in a Carabao Cup tie in August at the age of 16 years and 75 days – is set to feature alongside veteran goalkeeper Dimi Konstantopoulos, his senior by 23 years, six months and two days.
The Greek, who turned 40 in November, is poised to be the first player to feature for the club in his 40s.
The club record is held by former player-manager Bryan Robson, who started and played against Arsenal at Highbury 10 days short of his 40th birthday on New Year’s Day 1997.
Pulis is expecting an “open game” this afternoon against Posh with the tie evoking memories of a League Cup quarter-final meeting in 1991-92 when Boro progressed to the last four after a replay win at Ayresome Park.
The pair also met in a fifth-round FA Cup tie in 1974-75 with the Teesside club again prevailing after a replay to book a quarter-final place.