He withdrew from the Monte Carlo Masters with a right-knee injury in April and missed most of the clay-court season, including the French Open.
Djokovic's return to No 1 when the new ATP rankings are released next Monday was sealed on Wednesday when the current holder of that accolade, Rafa Nadal, had to pull out of the Paris event with an abdominal injury.
He won the first set comfortably, and then Dzumhur retired while trailing 1-2 in the second set.
Announcing his withdrawal at a hastily arranged press conference Nadal said: "My abdominal muscles haven't felt good for the past few days, especially on serve, doctors recommended that I didn't play". I've played him many, many times and we practise a lot.
After the Paris indoor tournament, the top eight players on the ATP tour will play the Finals - the traditional season finale - in London from November 11.
Until lunchtime on Wednesday, the tennis fans of Paris were buzzing about a glittering order of play that featured both Roger Federer and Rafael Nadal.
When asked for the reasoning behind the decision, the 37-year-old replied: "I prefer not to play".
Djokovic, looking in much sharper form than his opening match against Joao Sousa, took the set in 39 minutes.
However, during the first set the Bosnian advised Djokovic that one of his shots, which was called out, actually landed in.
He added: "I don't know if we can talk about a real injury. Everybody was sure he would be back to his best and I am happy to see someone like him back playing at that high level".
Japanese Nishikori beat Frenchman Adrian Mannarino 7-5 6-4 while American Isner battled past Mikhail Kukushkin 6-3 6-7 (2-7) 7-6 (7-1).
Federer has returned to Bercy event after a three-year absence, chasing his 100th career title after claiming the Swiss Indoors crown last week.
The 31-year-old's elevation is remarkable as it comes just five months after he slumped to 22 in the world - his lowest ranking for 12 years - when he was knocked out of the French Open in the quarter-finals.
Meanwhile, fifth seed Marin Cilic cruised into the third round with a 6-3, 6-4 victory over German veteran Philipp Kohlschreiber.
On Monday, they kept the projected jackpot at $1.6 billion but will re-examine the numbers Tuesday to decide if it should go up. A 2016 Powerball jackpot that was worth $1.58 billion is the current record-holder for largest jackpot in history.
President Donald Trump is wrapping up a visit to Western states with a campaign rally later Saturday in rural Elko, Nevada. Another boon for Republicans is that the Democrats' lead on the midterms narrows in battleground districts.
The Jacksonville Sheriff's Office said the shooting occurred just a half-mile away from TIAA Bank Field where the Jaguars play. Ron Lendvay, director of investigations for the Jacksonville Sheriff's Office , said several shots were fired about 12:35 p.m.
Aubameyang then doubled his tally nearly immediately in the 66th minute, tapping into an empty net thanks to some magic from Ozil. The Arsenal captain took to Twitter to hail his side after turning in a man of the match performance in the Premier League.
AK Bassi, who was probing the case against Asthana, was dispatched to Port Blair in public interest with immediate effect. Delhi Police and the Central Bureau of Investigation (CBI) teams are looking into the matter.
US President Donald Trump on Monday took aim what he called weak US immigration policy, declaring himself to be a nationalist . If he loses to O'Rourke, however, Trump may start calling him something else.
Kamala Harris, D-Calif., former CIA Director John Brennan and former Director of National Intelligence James Clapper. Aaronson said he did not know what made Sayoc seem emotional but noted he is facing decades in prison if convicted.
The brawl was ultimately halted after several players on both teams and security officials intervened to pull the fighters away. Paul alleges Rondo spit in his face which forced Paul to stick a hand in Rondo's.
In order to improve upon costs, Tesla offered customers a mid-size range version of the Model 3 which started at Dollars 46,000. Tesla also posted $52 million (£40.5 million) from the sales of regulatory tax credits and $23 (£17.9) million in other income.
José Mourinho has come under heavy fire this season, both from United fans and from the wider footballing community. They need great players, great movements, creative football to identify themselves to a player or a team.
The Red Dead Redemption 2 companion app is now on track for October 26, 2018, alongside the Xbox One and PlayStation 4 release. The Xbox One S is Microsoft's entry-level Xbox One console, granting access to all Xbox games on a budget.
Musk said on Twitter that the Boring Co. will hold an opening event to showcase the test tunnel on the night of December 10. The tunnel beneath the L.A. suburb of Hawthorne acts as a proof of concept for the Boring Company's proposed loop system.
The number of migrants swelled to about 5,000 as more people continue to join the group that stretches for about a mile. On Friday, US President Donald Trump thanked Mexico for holding back the migrants from crossing into the US.
If the existing US/China trade-war escalates, UBS foresees lower economic growth in both countries before policy responses. The Chinese cohort is 97 percent self-made, many of them in sectors such as technology and retail.
If a club can stump up €215m then they can sign Neymar - but only in the summer of 2020 and not before. The Paris-Saint Germain star cost £198m when he moved to Paris from Barca in 2017, a world-record fee.
Earlier in the press conference he explained how "the first thing I do, even as a player, is self-reflect: what did I do?" However, domestically they trail league leaders Hearts by eight points and Gerrard has issued another warning.
Daniels said: "I'm touched by all of the comments from Glenn's family and those in the football and broadcasting world". He won the FA Cup and UEFA Cup with Spurs and also played for Monaco , Swindon and Chelsea .
But some big spenders on ads "related to issues of national importance " appear to be vendors chiefly interested in making money. Also among the top spenders is the oil company Exxon Mobil, which has spent nearly $2 million on ads on Facebook since May.
Her exit from NBC News is not official yet. "But I'm not going to be one of the ones piling on Megyn Kelly at this time". A source revealed to People that the network had been reassigning Megyn Kelly Today workers to other roles.
US national security adviser John Bolton told Putin on October 23 that Washington would press ahead with plans to quit the treaty. Interested in Russia? Add Russia as an interest to stay up to date on the latest Russia news, video, and analysis from ABC News .
The blackface thing is a pretext, a "socially acceptable" reason for ending the Kelly experiment at NBC abruptly. The network reportedly told Megan Kelly Today staffers not to worry about their jobs on Wednesday.
Turkish officials suspect Khashoggi was killed inside the consulate by Saudi agents and his body cut up. Qahtani, along with several other senior officials, have been fired from their government positions.