Novak Djokovic returned to action for the first time since becoming a father with a straight-sets win over Philipp Kohlschreiber at the Paris Masters.
The Serb, 27, won 6-3 6-4 seven days after his wife Jelena gave birth to their first child, Stefan.
Djokovic is trying to protect his world number one ranking, with Roger Federer closing in on him following victory at the Swiss Indoors on Sunday.
Federer will open his campaign on Wednesday along with Andy Murray.
The 33-year-old Swiss, who like Djokovic and Murray had a first-round bye, faces France's Jeremy Chardy in his opening match and needs to continue his fine run of form in Paris if he is to overtake Djokovic in the standings.
|1st - 11,510 points||Novak Djokovic||Ser|
|2nd - 9,280 points||Roger Federer||Swi|
|3rd - 8,195 points||Rafael Nadal||Spa|
|4th - 5,385 points||Stanislas Wawrinka||Swi|
|5th - 4,485 points||Tomas Berdych||Cze|
|6th - 4,465 points||David Ferrer||Spa|
"I'm trying to take as much positive energy as I can from what's happened in the past few weeks," Djokovic said after his second-round win over Germany's Kohlschreiber.
"I'm very proud to be a father and I'm very proud of my wife for handling the birth in a great way.
"She's back home recovering now, with our little boy. This was my first match as a father and it can only inspire me to play my best tennis."
Murray will take on Frenchman Julien Benneteau on Wednesday (around 13:00 GMT), three days after winning an epic Valencia Open final against Tommy Robredo - the Scot's third title in a punishing five-week period.
Murray is fifth in the race to qualify for next month's ATP World Tour Finals, and needs to reach the quarter-finals to be certain of a place in London.
However, he would require an unlikely combination of results to deny him one of the four places still available.
"My expectations this week aren't incredibly high," Murray told BBC Sport.
"I have to try to be realistic. I've played a lot of tennis the last few weeks but I've recovered well from the tough matches, which I wasn't doing earlier in the year.
"London is close, it would be nice to get there, but if not we'll get ready for 2015 and hopefully have a strong start there. We'll see."
Robredo was back on court on Tuesday and again taken to a final set tie-break, beating Canada's Vasek Pospisil 6-3 4-6 7-6 (7-5), and Murray expects to suffer when he returns on Wednesday.
"I would imagine I'd be fatigued - if I'm not then something's probably not quite right with me; that would be a bit strange," said the former Wimbledon champion.
Fifth seed Tomas Berdych, currently eighth in the Race to London, beat Adrian Mannarino 6-4 6-7 (3-7) 6-2 to maintain his London bid.
Andy Murray's Paris Masters match against Julien Benneteau will be live in the UK on BBC Radio 5 live Sports Extra. Play is scheduled to start around 13:00 GMT on Wednesday.