Four documents in Nasa leader Raila Odinga's petition challenging the re-election of President Uhuru Kenyatta were filed after the deadline, according to the Supreme Court, even as the coalition said the papers were not key to their case.
The court's registrar, Ms Esther Nyaiyaki, said in a letter to Mr Odinga's lawyers on Monday that the Supreme Court has received two complete sets of 59 volumes of their petition and that, on Sunday, the lawyers submitted six more.
She also said that three key documents were missing from the National Super Alliance's petition.
Last evening, however, Nasa lawyer Paul Mwangi said the documents were annexures that were missing in some of the primary documents, which were filed before the deadline.
"They are Forms 34 A. They are not primary documents.
"However, a document is deemed to have been filed when it was paid for and, in this case, that was done before Friday midnight. That is the legal position," Mr Mwangi said by telephone.
Wrote Ms Nyaiyaki in the letter to Murumba and Awele Advocates copied to the lawyers for the Independent Electoral and Boundaries Commission's (IEBC), Iseme, Kamau and Maema Advocates and Ogetto, Otachi and Company Advocates: "As at 21st August, 2017, our records are still missing one copy of volume 31, 55 and 56."
She added that on Sunday, the firm presented additional volumes -- 60, 61, 62 and 63 -- which she said were mistakenly stamped as having been received on August 18.
"The same have since been rectified to reflect the actual date they were filed, that is, 20th August, 2017," Ms Nyaiyaki said.
"Kindly note that this date is deemed as the actual date of filing of volumes 60, 61, 62 and 63."
The submission of documents past the seven-day deadline for filing of a petition could become contentious in the eagerly awaited case, which is expected to capture the attention of the nation for the next two weeks.
On Sunday, IEBC lawyers flagged this as a possible sticking point when they wrote to Mr Odinga's lawyers lamenting their inability, at the time at least, to get hold of the petition filed on Friday night.
"Upon enquiring from the Supreme Court, we were advised that you were still filing documents as at midday today.
"Our client is concerned as to why documents are still being filed way out of time," the firm said in the letter signed by Mr Kamau Karori.
The law firm also asked Ms Nyaiyaki "to confirm which documents are being filed this long after the deadline for filing".
The contention over the late filing has echoes of the 2013 presidential election petition, when the Supreme Court threw out a 900-page affidavit filed by the now-defunct Coalition for Reforms and Democracy (Cord) on the basis that it was filed out of time.
Another contentious issue could arise if the Attorney-General, Professor Githu Muigai, attempts to join the case as a friend of the court, known in legal lingo as amicus curiae.
But Mr Mwangi said: "We will contest his application. Previous positions he has taken in pre-election litigation clearly show he is partisan."
Last evening, the Supreme Court, which has only 14 days to hear and determine the case, issued new deadlines for the petitioner and respondent as it gears up for the hearing.
Chief Justice David Maraga said Mr Odinga's team should send its written submissions by Friday 1pm and the IEBC, its chairman Wafula Chebukati and President Kenyatta by 7pm.
Should the Nasa lawyers wish to file a rejoinder to what the IEBC and President Kenyatta say, they should do so at the court and serve it to them by 9am on Saturday.
According to changes made to the Supreme Court Act late last year, the electoral agency should submit all its Forms 34A, 34B and 34C by Tuesday (August 22), which is 48 hours after being served with the petition.
There are 40,883 Forms 34A, 290 Forms 34B and one Form 34C, making it a total of 41,174 documents.
Mr Odinga's team has separately also asked for the IEBC to surrender to the court the 40,883 gadgets used to identify voters and transmit results on Election Day.
This came as the Jubilee Party on Monday said that it will not join the petition and will, instead, package its case in defence of President Kenyatta.
"We are fully prepared, and we are going to push a united front of arguments on behalf of the President, who is listed as a respondent alongside IEBC and its chairman," a lawyer in the team who did not wish to be named said.
Unlike in 2013, however, Mr Odinga has not named Deputy President William Ruto as a respondent.
Mr Odinga filed his case some minutes to midnight on Friday, paving the way for a rigorous, 14-day marathon courtroom battle.
"A person may file a petition in the Supreme Court to challenge the election of the President-elect within seven days after the date of the declaration of the results of the presidential election," Article 140 (1) of the Constitution states.
Mr Odinga's legal team then had up to two days to serve the respondents -- President Kenyatta, the IEBC and its chairman in his individual capacity as the presidential elections returning officer.
The three respondents, who were served on Sunday, now have four days to file their responses.