Two goals in 10 minutes early in the second half from All Boys midfielder Oscar Ahumada and striker Angel Vidozo, who converted a penalty, left Boca with four points out of a possible nine in the 'Final' championship after Saturday's match.
"I'm worried like every time we lose a match. I'm not going to state publicly the faults we know we have and we'll keep working to try to repair them," Bianchi told reporters.
Former Argentina playmaker Juan Roman Riquelme is working on his fitness preparing to come back from a seven-month break from football to help the man with whom he shared in a string of titles in previous spells at the club.
Boca were fortunate to win their opening match of the 'Final', second of two championships in the season, fighting back from two goals down to beat Quilmes 3-2 at home after goalkeeper Agustin Orion had saved a penalty two weeks ago.
They have since been upset 2-1 at home by Mexico's Toluca in the Libertadores Cup, South America's elite club tournament they have won six times, and drawn 0-0 at Tigre in the league last weekend.
"We have gone backwards since the Tigre match," Bianchi said. His side have given away penalties in three of their four matches in all competitions.
'Inicial' winners Velez Sarsfield fell 1-0 away to Lanus, the team fast emerging as their most serious contenders for the 'Final' title.
Striker Silvio Romero scored to take his tally to three and Lanus lead the standings with a perfect record of nine points from three matches and eight goals scored to none conceded.
Former Deportivo La Coruna and Real Sociedad defender Gabriel Schurrer quit as coach of Argentinos Juniors after his side's 2-1 home defeat by Arsenal.
Argentinos picked up one point in seven matches under Schurrer, who took charge in mid-November. He is the 12th coach to lose his job in the season.
A possible successor to Schurrer could be Diego Maradona although he is tied to a contract as a consultant in the United Arab Emirates until June.
Schurrer went into Saturday's match at the Diego Armando Maradona ground angry that club president Luis Segura had named the former Argentina captain and coach in a radio interview as someone he would like to see at the helm at Argentinos Juniors.
